Studies on the Parasitic Helminths of the North Central States. I

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5-1948

Studies on the Parasitic Helminths of the North Central States. I. Helminths of Sciurida

Robert L. Rausch University of Washington, [email protected]

Jack Tiner University of Illinois at Urbana-Champaign

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Rausch, Robert L. and Tiner, Jack, "Studies on the Parasitic Helminths of the North Central States. I. Helminths of Sciurida" (1948). Faculty Publications from the Harold W. Manter Laboratory of Parasitology. 572. https://digitalcommons.unl.edu/parasitologyfacpubs/572

This Article is brought to you for free and open access by the Parasitology, Harold W. Manter Laboratory of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Faculty Publications from the Harold W. Manter Laboratory of Parasitology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

Studieson theParasitic Helminths of theNorth CentralStates. 1.Helminths of Sciuridae* RobertRausch Departmentof VeterinaryScience, College of Agriculture, Universityof Wisconsin,Madison

JackD. Tiner** Depa.rtmentof Zoology and Physiology,University of Illinois, Urbana

It is acceptedthat a fairdegree of completenessis being achievedin our knowledgeof North Americanmammals and birds. It can be assumed that nearlyall the describedspecies of the highervertebrates are parasitizedby helminths,but many of these helminthsprobably remain undescribed,and little is known of their geographicaldistributiotn. Very little informationis availableon the incidenceof the parasites,or theireffect on the host. Informationconcerning host-parasite relations should be cf interestto workersin wildlifemanagemenlt, in order to have a more nearlycomplete knowledgeof the ecologyinvolved. The writersconcede that fromthe stand- point of helminthologyalone, informationpertinent to life cyclesis of basic importanceat present.However, we hope that surveydata can be used to advantageby thosewishing to conductsuch research. Over the past fewyears, beginning in 1942, we have made examinationsof a large numberof animalsrepresentative of the fauna of the North Central States,and it is our intentionto presentthe resultingdata, by host group,as theyare completed.While it is true,in some cases, that additionalexamina- tions would yield informationof value, circumstanceshave often made it necessaryto discontinuework with a given group afterstudying only a fairly representativeseries of specimens.In orderto use the timemost economically, we have followedthe practiceof co'lectingwithout concentration on a single group or species.This has also contributedin part to a lack of an adequate numberof animalsfrom some localities. The planningof thisstudy, and mostof the Ohio and Michigancollecting, was carriedout by the seniorauthor, who is also responsiblefor cestodeand trematodeidentifications. The junior authoridentified the nematodesencoun- tered,and assistedin collecting.We regretthat therewere no specialistsin such fieldsas entomology,bacteriology, and mammalogyavailable to make furtheruse of the materialwhich came throughour hands.Whenever possible, studyskins and skulls of this and othermaterial were deposited in recognized collections.

6 A contributionfrom the Departmentof VeterinaryScience, Universityof Wisconsin. The work done in Wisconsin was supportedin part by the Research Committeeof the Graduate School from funds supplied by the 'WisconsinAlumni ResearchFoundation. 4 Formerlyof the Universityof Wisconsin.

1948 RAUSCH ET AL.: HELMINTHS OF SCIURIDAE 729

The carefully-organizedcollaboration of Elton,Ford, Baker, and Gardner (1931) in theirinvestigations of the diseases and parasitesof rodentsshould standas a modelfor this type of study.

Source of Material A totalof 325 sciurids,collected by the writers in Ohio,Michigan, Illilnois, and Wisconsin,was examined,among which the followingwere represented: foxsquirrel, Sciurus niger rufiventer Geoffroy; southern gray squirrel, Sciurus c. carolinensisGmelin; northern gray squirrel, Sciurus carol nensis leucotis Gapper;red squirrel,Tamiasciurus budsonicus subspp.; chipmunk, Tarnias striatussubspp.; eastern flying squirrel, Glaucomys v. volans(L.); northern flyingsquirrel, Glaucomys sabrinus macrotis Mearns; 13-lined ground squirrel, Citellust. tridecemlineatus(Mitchill); Franklin's ground squirrel, Citellus franklini(Sabine); woodchuck,Marmota monax subspp. Certain of these werenot identifiedto subspecies,since this has littlevalue in the present study,and suchidentifications are often difficult without large series for com- parison.The hostnames are accordingto Bole and Moulthrop(1942), and Burt(1946). In additionto thespecimens mentioned above, through the kindnessof Dr. ClarenceE. Mickel,a numberof helminthsfrom Minnesota sciurids was madeavailable to us forexamination. This collectionincluded the helminths ftom11 leastchipmunks, Eutdmias minimus jacksoni Howell; 1 graysquirrel, S. carolinensisbypophaeus Merriam; 3 foxsquirrels, S. nigerrufiventer; one 13-linedground squirrel, C. t. tridecemlineatus;and 3 woodchucks,M. monax subsp.With the author'spermission we have also includedthe unpublished resultsof thesurvey of Ohio squirrelsby Katz (1938), whichwas basedon the examinationof 72 southerngray squirrels, S. c. carolinfnsis;and 16 fox squirrels,S. nigerrufiventer. The localitiesfrom which the materialwas examinedare shownon the map (Fig. 1) to thenearest county. The counties,according to thenumbers usedto designatethem, are as follows:

OHIO MICHIGAN 23.Dodge 1.Butler 13.Ingham 24.Fond du Lac 2. Darke 14.Cheboygan 25.Shawano 3. Wood ILLINOIS 4. Seneca 15.McHenry MINNESOTA 5.Wyandot WISCONSIN 26.Fillmore 6. Marion 16.Barron 27.Scott 7.Union 17.Buffalo 28.Hennepin 8. Delaware 18. Jackson 29. Ramsey 9. Franklin 19. Juneau 30. Carlton 10. Fairfield 20. Satuk 31. St. Louis 11. Scioto 21. Dane 32. Cook 12. Ashtabula 22. Columbia 33. Carver The localitiesare referredto belowin the separateconsiderations of the helminths,in orderto show theirdistribution. The parasitedistribution is Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

730 THE AMERICAN MIDLAND NATURALIST 39 (3)

* 16'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

20 23 13~~~~~~~~1

Fig. 1.-Map of the North Central States showinglocalities from which material for this studywas obtained. Counties in solid black are those from which the host animalswere examinedby the writers. consideredirrespective of host species, since the number of hostanimals examinedwas notsufficient to allow otherwise.

Results A totalof at least 33 speciesof helminthswas encounteredduring the courseof the presentstudy. The resultsof the examinationsmade by the writerare shownin Table 1. Data takenfrom the work of Katz (1938) are listedin Table 2, and thoseregarding the Minnesotamater al are shownin Table 3. It shouldbe notedhere that the total number of Minnesotasciurids examinedwas not known,so no informationis available concerning incidence of helminthsfrom the animals of thatarea. The helminthsare consideredseparately below, according to species.The numbersin parenthesesrefer to the countieslisted above, and indicatedon themap (Fig. 1). Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

1948 RAUSCHET AL.: HELMINTHSOF SCIURIDAE 731

CESTODA Nine species of cestodeswere collectedby the writers;of these, 6 were adult, and 3 were larval forms.Cestodes, in general,were uncommon.in tree squirrels,but abundantin groundsquirrels from some localitics.

ANOPLOCEPHALIDAE 1. Catenotaeniapusilla (Goeze, 1782) (11, 14, 18, 21). Found in the small intestineof the host,this cestodewas collectedby the writersfrom one fox squirrel,and fromthree northern flying squirrels. Katz (1938) recorded what was probablythis species fromthe southerngray squirreland the fox squirrel.All infectionswere light, consisting of but a singleworm each, except fol one animal whichcontained two worms.The life cycle of C. pusilla has recentlybeen elucidated by Joyeauxand Baer (1945), and the intermediatehost was shown to be a mite. These workers,as a resultof theirinvestigations, removedthe genus fromthe familyDilepididae, and placed it in the family Anoplocephalidae. 2. Andryasciuri Rausch, 1947 (18). Parasiticin the small intestineof tha host, the presentspecies was taken twice from the northernflying squirrel. Another memberof the genus, A. primordialisDouthitt, 1915, has been recordedfrom North Americansquirrels, but we did not encounterit. Unfor- tunately,we were not able to obtain enough specimensof the host animal to determinehow commonlyA. sciurioccurs, or whatits geographicaldistribution mightbe. Althoughthe life cycleof cestodesof this genus is not known, the intermediateform is possiblyfound in a mite,as is the case withthe other membersof the familywhere the life cycleis known. The helminthsfound in the two speciesof flyingsquirrels examined by us differedsufficiently that it would be of considerableinterest to examineanimals flom the area wherethe rangesof thesespecies overlap.

HYMENOLEPIDIDAE 3. Hymenolepisdiminuta (Rudolphi, 1819) (3, 11, 16, 18, 21, 23, 24, 25, 29). Parasiticin the small intestineof the host. Although commonin groundsquirrels in some areas, this cestodeoccurred rarely in tree squirrels. Katz (1938) recordedwhat was probablythis speciesfrom the southerngray squirreland fox squirrelin Ohio; we collectedthe speciesonly in Wisconsin, however.As manyas 42 specimensof this cestodewere taken from the small ii-testineof a single13-lined ground squirrel; ordinarily flom 1 to 6 specimens werepresent. The treesquirrels, Franklin's ground squirrel, and the chipmunk infectedwith this species contained a singlespecimen each. The two specimens examinedfrom tree squirrels were much larger than any of the others. McLeod (1933) describedHymenolepis citelli fromground squirrelsin Manitoba.Except for the singlespecimen from the chipmunk,discussed below, all specimensof Hymenolepis collected by us fromsquirrels agree closely withMcLeod's description.However, we were not able to differentiatethem fromspecimens of H. diminutataken fromOhio rats. Since the characters Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

732 THE AMERICAN MIDLAND NATURALIST 39 (3) used by McLeod seem to be somewhatvariable, we recommendthat H. citelli (McLeod, 1933) be considereda synonymof H. diminuta(Rudolphi, 1819). Hughes (1941) did not considerH. citelli in his key to the species of the genus Hymenolepis. 4. Hymenolepissp. (21). Found in the largeintestine of the host,a single, incompletespecimen was taken froma chipmunkcollected at Madison, Wis- consin.Specific determination was not possible,but it resembledsomewaht H. fraternaStiles, 1906, in its morphologicaldetails.

MESOCESTOIDIDAE 5. Mesocestoideslatus Mueller, 1928 (13). A single large worm belonging to thisspecies was takenfrom the small intestineof a foxsquirrel, collected at East Lansing, Michigan. This parasite has not previouslybeen recorded fromsquirrels, and certainlyit is not a commonparasite of this host group. Although a considerablenumber of fox squirrels (44) was examinedfrom the same area. and most of these fromthe same woodlot fromwhich the infectedanimal was collected,no otherinfection by this cestodewas detected. It is worthyof note that other mammals (raccoon and opossum), collected from the same woodlot, were rathercommonly infected with M. latus. In view of the life cycle of this group of cestodes (Schwartz, 1927), it seems unlikelythat squirrelsordinarily would be exposed to infecrion.It was of interestto note thatmanv gravidsegments were presentin the strobilaof this specimen. TAENIIDAE 6. Taenia pisiformis(Bloch, 1780) (13). A singleinfection by this parasite was recorded.Eleven cysticerciwere removedfrom the body cavityof a fox squirrel.Brown and Yeager (1945) reportedthe species fromsquirrels in Illinois,but it cannot be considereda commonparasite of squirrels.Since therewas a high infectionof rabbitsin the intermediatearea, and since dogs were commonlyfound in the woodlot fromwhich the infectedsquirrel was collected, it seems that squirrelsmust ingest numerous eggs which never develop. It would be most interestingto know whythis developmentcan take p3acein certainindividuals only, as is apparentlythe case. 7. Taenia taeniaeformis(Batsch, 1786) (13). Larval formsof this cestode wereremoved twice from liver cysts of the fox squirrel.It has previouslybeen recordedfrom North Americansquirrels, but is not a commonparasite in this group.It is of interestto note that the two infectedsquirrels were taken during the wintermonths of Januaryand February.Concurrent work with the meadowvole (Microtusp. pennsylvanicusOrd), of which345 specimenswere examinedfrom a field adjacent to the woodlot wherethe infectedsquirrels were collected, showed a definitepeak of infectionwith T. tamniaeformis during winterand early spring. Nine per cent of the voles were infected. Accordingto Miller and Gardiner (1934), the presenceof cysticerciof this species in rats confersan active immunitywhich preventsthe onchospheres fromestablishing themselves during any subsequentexposure. Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

1948 RAUSCH ET AL.: HELMINTHS OF SCIURIDAE 733

8. Unidentifiedcestode. (13). Fragmentsof a singlecestede were taken fromthe smallintestine of a red squirrel.The conditionof thesewas such thatidentification was not possible. 9. Unidentifiedcysticerci. (23). Six verysmall cysticerci, some of which weredegenerating, were removed from the liver of a single13-lined ground squirrel.It is possiblethat these are larvalforms of one of thebird cestodes, suchas Cladotaenia.Since ground squirrels form a majoritem in thediet of thebadger, one might expect cysticerci of thebadger cestode, Taenia taxidien- si Skinker,1935, to be foundin thesesquirrels. When compared with adult wormsfrom badgers, however, it was foundthat the hooks differed greatly. A doublerow of 38 hookswas presenton the cysticerci;these measured 15 and 6 ju long. TREMATODA Trematodesare uncommonin theNorth American sciurids. We collected otnlythree species belonging to thisgroup.

NOTOCOTYLIDAE 10. Quinqueserialishassalli (McIntosh and McIntosh,1934) (21). A heavyinfection of thisspecies of trematodewas encounteredin thececum of a singlewoodchuck, from which it has not previouslybeen reported. The infectedanimal had itsden at theimmediate margin of a large,stagnant pond, and snails,probably ingested with vegetation, were found in theintestine when theautopsy was made.Infection with this parasite might depend much more uponthe habitat and foodhabits of thehost than upon natural immunity. In thearea covered by us, the meadow vole is theonly other host from which we haverecorded this trematode. DIPLOSTOMIDAE 11. Fibricolanana Chandlerand Rausch,1946 (13). Two specimensof thistrematode were taken from the smallintestine of a red squirrel.It is probablethat such small helminths as theseare oftenoverlooked in routine examinations,since they only can be detectedwhen the intestinalcontent is examinedunder the low power of themicroscope. The lifecycle is notknown. As pointedout previously(Chandler and Rausch,1946) thisis apparently thefirst strigeid to be recordedfrom sciuricis.

BRACHYLAEMIDAE 12. Scaphiostomumpancreaticum McIntosh, 1934 (21). One of the few kelminthsencountered which occurred outside the intestinal tract, S. pancr- aticumwas foundin the pancreaticducts of the chipmunk.This trematode was firstrecorded (McIntosh, 1934) fromnorthern Michigan. We foundit onlyin Wisconsin,where most of thechipmunks examined were collected. It was foundin adultanimals only, although several young, nearly full grown, wereexamined. It is of interestto notethat the infected animals were taken neara largelake. It is notclear to us whateffect the parasite might have on thehost. Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

734 THE AMERICANMIDLAND NATURALIST 39 (3)

NEMATODA Most of the helminthsencountered by us in sciuridsbelonged to this group. Nematodes occurredin larger numbersthan did eithercestodes or trematodes. STRONGYLOIDIDAE 13. Strongyloidessp. (13, 16, 20, 21). This nematodewas founduncom- monlyin the small intestineof threespecies of tree squirrels.Because of its small size, it mightbe veryeasily overlooked.Chandler (1942) describedS. robustusfrom squirrels in Texas. S. papillosus (Wedl) was recordedfrom the southerngray squirrel by Reiberand Byrd (1942).

TRICHOSTRONGYLIDAE

14. Citeilinemd bifurcatumHall, 1916 (1, 3, 6, 11, 13, 15, 17, 18, 19, 21, 22, 26, 28, 32). The mostcommon nematode found by us in the sciurids, C. bifurcatumhas been recordedfrom several host speciesover an area extend- ing fromColorado, Wyoming,and Saskatchewaneastward to Maine. It has not been foundsouth of Tennesseeand Maryland,nor in east Texas. Infec- tions were usually lightin the animals examinedby us. In the fox squirrel from1 to 42 specimenswere found, with an averagenumber of 9. 15. Heligmodendriumhassalli (Price, 1928) (11, 16, 17, 18, 20, 21). Aithoughfairly common in Wisconsin,the writersdid not find this species in sciuridscollected from the rest of the region.Katz (1938) recordedthis speciesonly fromthe southerntip of Ohio, whereits incidenceappeared high, and Price (1928) recordedit fromMaryland. Harkema (1936), Chandler (1942), and Graham and Uhrich (1943) have reportedthis nematodefrom areas farthersouth than those fromwhich C. bifurcatumhas been recorded. Data concerningthe distributionof both speciesappear to be far fromcom- plete. Infectionswere generally light in the threespecies of treesquirrels from whichwe recordedthis helminth,although in one case 438 wormswere taken froma singlefox squirrel. 16. Trichostrongyluscalcaratus Ransom, 1911 (20, 21). This nematode,a commonparasite of rabbits,was found in the fox and gray squirrelsin Wis- ccnsin A single male, with unusuallyshort spicules,but which otherwise resembledthis species,was found in the chipmunk.T. calcaratusis, however, evidentlybetter adapted to rabbitsthan to squirrels.We did not find it in squirrelsin Ohio or Michigan,although it has been taken fromrabbits from both areas, and in some cases fromimmediate woodlots from which squirrels were collected.In Wisconsina maximumof 2 specimenswas removedfrom a single sciuridhost; on otheroccasions isolated male or female specimens occurred.In one instance,a singlemale T. calcaratus,in conjunctionwith 33 Strongyloidesfemales, caused considerabledifficulty in the identificationof the latter.Graham and Uhrich's (1943) findingof 11 specimensin a single fox squirrelwould indicatethat this animal may serve as host to moderate numbersof thishelminth, on occasion.The life cycleof T. calcaratusis direct. Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

1948 RAUSCH ET AL.: HELMINTHS OF SCIURIDAE 735

17. Obeliscoidescuniculi (Graybill,1924) (6, 7, 13). Apparentlya common parasiteof the woodchuckin Missouri,Ohio, Michigan,and Minnesota (Rausch and Tiner, 1946). Accordingto the reportby Dalke (1942), 0. cuniculishows a definitedecrease in the cottontailduring the wintermonths. Erickson(1944), however,found higIhinfections in the snowshoehare in the spring(March). While we unfortunatelyhad an insufficientnumber of wood- chucksto check this, it was noted that all infectedwoodchucks were taken duringthe monthof July,or laterin the summer.This perhapsindicates that the woodchuckis relativelyfree from this parasitewhen emergingfrom hiber- nation.We found9 woodchucks,collected before July 1, to be freefrom this paarsite,while 8 animals,collected after this date, were infected,and 4 were uninfected. 18. Boehmiellawilsoni Lucker, 1943 (17, 21, 33). Interestingquestions as to the epidemiologyof B. wilsoniseem to be posed by the factthat infections withit wererare and minimal.Five out of a total of 39 grayand fox squirrels takenin the vicinityof Madison, Wisconsin,were infected w th a singlefemale each. We did not findthis parasitein the rest of Wisconsin,'but a single male came fromMinnesota. United States National Museum recordswould indicatethat it was collectedon threeoccasions from the southeasternstates of West Virginia,Virginia, and Georgia duringthe years1897-1943 (Lucker, 1943). The unusuallylarge size of this trichostrongylemakes its detection almost inevitablewhen the stomach wall and contentsare examined with ordinarycare. OXYURIDAE 19. Enterobiussciuri Cameron, 1932 (7, 13, 15, 21). This was the common helminthparasitic in the eastern flyingsquirrel. It was of especial interestthat, from an area with a radius of about one-halfmile, 73 sciurids of 5 species were taken (East Lansing, Michigan), of which only 8 were infectedwith this worm.Six of 11 flyingsquirrels and 2 of 53 fox squirrels were parasitizedby E. sciuri.Two chipmunks,5 red squirrels,and 2 wood- chuckswere not infected.Of two Wisconsin fox squirrelsthat harboredthis nematodein the cecum,one containedonly a gravidfemale, while the other was extremelyemaciated, apparently because of a severe case of mange (a conditionrather commonly observed by us in at least 3 squirrelspecies, and whichon a few occasionsobviously was the cause of the death of the host). and harboredseveral hundred E. sciuri of all ages, including40 gravid fcmales.It has been collectedfrom the easternflying squirrel in Ohio and northernIllinois, but we have so far failedto findthe northernflying squirrel infected.As far as we have been able to determine,this parasite,described fromthe Americangray squirrel in Scotland,has not previouslybeen recorded fromthis continent.Our data would indicatethat it is an Americanspecies, and that the flyingsquirrel is the normalhost in the North Central States. In all cases, the nematodewas found in the cecum of the host. Future workersare cautionedto use carefulsedimentation methods, and to examine the sedimentunder the low-powermicroscope, in orderto findthis helminth, which is readily overlookedbecause of its extremelysmall size. Life cycle Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

736 TIHE AMERICAN MIDLAND NATURALIST 39 (3)

studieson E. sciuirimight be of interest,since it is remotelyrelated to a human parasite. 20. Syphacia thompsoniPrice, 1928 (14, 18). This nematodeoccurred in atl of the 5 northernflying squirrels examined by us, but it was not foundin the easternflying squirrel. Price (1928) describedS. thompsonifrom the latterspecies in Virginia. The persistentfailure of North Americaninvesti- gatorsto findthis parasitein othersciurids might indicate a high degreeof host specificityfor flyingsquirrels. However, Li (1933) has reporte:lS. thompsonifrom Sciurus vulgarisand Sciurotamiadavidianus in China. 21. Syphaciasp. (32). Fourd only in the cecumand largeintestine of the least chipmunk,this nematode appears to representan undescribedspecies. Its descriptionis beingundertaken by the juniorauthor. We have no idea of the distributionof this helminth,since the host animal was not obtained from Michigan and Wisconsin where,in the area considered,it also occurs. The reportof Syphacia sp. in large numbersin the Californiaground squirrel by Linsdale (19.46) and the findingof a singleS. obvelatain Eutamias amoenus by Rankin (1945) are of interest,especially since femalesof the present speciesare not easilydistinguished from S. obvelata. 22. Citellina marmotaeManter, 1930 (14, 30). Manter (1930) has recordedthis helminthfrom Maine, and we are able to extendits range to northernMichigan and Minnesota.Of the two infectionsfound by us, one was quite heavy,with an excess of 400 worms,while the otherwas lighter, withabout 100 wormns. ASCARIDIDAE 23. Ascarissp. (6, 7, 9, 21). Immatureascarids were found by the writers oni threeoccasions. Katz (1938) reportedAscaris lumbricoidesLinnaeus, 1758, fromsquirrels, as did Brown and Yeager (1945). However, since Linsdale (1946) has reportedwhat appeared to be A. columnarisLeidy, 1856, from the Californiaground squirrel,Citellus beecheyi (Richardson), we do not considerour materialadequate fordefinite specific determination. The squirrels examinedby the writermight easily have becomeinfected with either species, since A. lumbricoidesis a commonparasite of swine,and A. columnarisis commonlyfound in some of the carnivores(raccoon, skunk, badger), in the regionwhere the materialwas collected.It seems questionablewhether these ascaridsare able to maturein squirrels.Perhaps it can be assumed that A. laevis Leidy, 1856, may be identicalwith one of the above formsrather than withT. pigmentatavon Linstow,1897, as has been suggestedby Hall (1916). Ascarislaevis was describedfrom a singlefemale occurring in the woodchuck.

THALAZIIDAE 24. Rictulariahalli Sandground,1935 (21). We are of the opinion that thespecimens of Rictulariafrom the graysquirrel and chipmunkin Wisconsin belongto the speciesof R. halli Sandground,1935, since the males found in these hosts seem to agree withSandground's description. It may be shown, by the studyof additionalmaterial, that R. halli is identicalwith the species Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

1948 RAUSCH ET AL.: HELMINTHS OF SCIURIDAE 737

discussedbelow, previously described by McLeod (1933). Infectionswith R. halli werelight (1 to 7 worms;average number 2 per host). As has been the usual experiencewith this genus, far more femalesthan males wererecovered. We do not, however,consider this a resultof overlookingthe males, because of theirsmall size, but ratherthat it is a peculiarityof the group.

25. Rictulariacitelli McLeod, 1933 (21, 29). We could not distinguisl the femalesof this species fromthose of R. halli; however,a comparisonof the singlemale collectedby us witha male loaned by Dr. McLeocdindicated that our materialfrom the 13-linedground squirrel cannot yet be considered identicalwith R. halli. This speciesoccurred more abundantly in the host than the precedingone (1 to 19 worms;average number 3.6 per host).

26. Rictulariasp. (6, 7, 8.) Collectedby us onlyin Ohio, and reportedby Katz (1938) fromthat area, and by Grahamand Uhrich (1943) fromsouth- east Kansas, this species closelyresembles R. onychomisCuckler, 1939, but differsin morphologicaldetails. Additional informationconcerning some of the species of Rictulariawill be presentedin the near future(Tiner, unpublisheddata).

SPIRURIDAE

27. Spirura michiganensisSandground, 1935 (21). This nematode was collectedonly fromthe chipmunk,in centralWisconsin. It is of interestto note, in connectionwith the followingspecies, that a considerablenumber of 13-linedground squirrels were taken within a quarterof a mile of the local'ty wherethe infectedchipmunks were collected.None of the chipmunkshad morethan 3 of thesenemato&es in the small intestine,with an averagenumber of 2 worms.

28. Spirura infundibuliformisMcLeod, 1933 (29). A single 13-lined ground squirrel,collected at St. Paul, Minnesota, was infectedwith this species. Dr. A. B. Erickson,St. Paul, Minnesota,should receivecredit for the original identification.The number of male pre-cloacalpapillae varies from10 to 12 on each side in this species,and from5 to 8 in S. michiganensis. This differenceappears to be the chief means of distinguishingthe two forms.

PHYSALOPTERIDAE

29. Physolopterasp. (21, 25, 29). Immature forms belonging to thisgenus were takenby the writersfrom the northerngray squirrel,Franklin's ground squirrel,and the 13-linedground squirrel. It also occurredin the latterspecies in Minnesota.Physaloptera massino Schulz, 1926, has been reported(Mor- gan, 1943) from the fox squirrel and 13-lined ground squirrel in Wisconsin and Minnesota, and McLeod (1933) has reportedthe same species from groundsquirrels in Canada. These nematodeswere uncommon in the animals examinedduring the courseof the presentstudy. Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

738 THE AMERICAN MIDLAND NATURALIST 39 (3)

TRICHURIDAE 30. Trichurissp. (21). This nematodeoccurred twice in the chipmunk, but materialwas not adequate to allow for specificdetermination. Members of this genus apparentlyare uncommonin sciuridsof this region,although theymay occur commonlyin otherrodents. 31. Capillariasp. (3, 7, 11, 15, 21). The small size of thisparasite, and its tendencyto adhere closelyto the intestinalwall, may accountin part for its seeming scarcity.Although recordedfrom the northerngray squirrel, Franklin'sground squirrel,chipmunk, and flyingsquirrel, it occurredcom- monlyin only the last two species,and in greatestnumbers (maximum of about 40) in the chipmunk.Katz (1938) recordedCapillaria sp. fromthe fox squirreland southenigray squirrel in Ohio. A few specimensof nematodeswere obtained,which, usually because of immaturity,could not be identified.These are not consideredhere, although theyare Iistedin Tables 1 and 3.

ACANTHOCEPHALA GIGANTORHYNCHIDAE 32. Macracanthorhynchushirudinaceus (Pallas, 1781) (6, 8). A total of 5 adult wormsof this specieswas taken fromtwo fox squirrels,collected in centralOnio, and a single immaturespecimen was found attachedto the mesenteryin the body cavityof a chipmunk,from the same area. The occur- rence of this helminthin squirrelshas previouslybeen reported (Rausch, 1946). The local distributionof this parasite,in its normalhost, is not clear. As far as we have been able to determine,it is not found over much of the area consideredin this paper.

MONILIFORMIDAE

33. Moniliformissp. (32). A few specimens belonging to this genus cccurredin the least chipmunkin Minnesota. The conditionof these was such, however, that specific determination was not made. Chandler (1941) recordedM. clarki (Ward, 1917) fromSciurus and Citellus in the "mid- Westernstates," and McLeod (1933) recordedM. spiradentatisfrom Citellus spp. in Canada. The status of the last-mentionedspecies is not clear. The occurrenceof Moniliformisin North American squirrelshas recentlybeen reviewedby Chandler (1947). Helminthsof thisgenus are uncommonin the sciurids of the North Central States, although they occur commonlyin squirrelsin otherareas (Chandler, 1947). We have recordedonly one other species of Moniliformis from this region, M. dubius, collected from moles, Scalopus aquaticusmacbrinus (Rafinesque), in Ohio.

Discussion

Although the ecology of the sciurid hosts has a close connection with their parasitismby helminths,it is doubtfulthat the changes which have Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

1948 RAUSCH ET AL.: HELMINTHS OF SCIURIDAE 739 occurredin the distributionof the squirrelsthemselves have greatlyaffected the parasites. The changesin land use whichhave taken place since settlcmentof the regionunder consideration have stronglyinfluenced the distributionand abun- dance of the squirrelspecies. This has been especiallyevident in the replace- mentof the graysquirrel by the foxsquirrel over much of the area, as clearing of the foresthas made suitable habitat for the latter.This has been well describedfor Michiganby Allen (1943). Except for isolatedcolonies (e. g. Columbus, Ohio, and Detroit, Michigan) the gray squirrelis now absent fromthe heavilycultivated, glaciated section of Ohio, and from southern Michigan.In southernWisconsin both speciesoccur together,and in Illinois this is also tlle case, withthe fox squirrelpredominating (Brown and Yeager, 1945). The 13-linedground squirrel becomes more abundantwith overgrazing of pastureland, and appearsto be extendingits rangeeastward, where it is now fcund to centralOhio. Franklin'sground squirrel is found as far east as the westernedge of Indiana. The latteris sporadicin its occurrencein southern Wisconsin,where the specimensexamined for the presentstudy were collected. The red squirrelis found abundantlyover Ohio and southernIVIchigan, especiallyalong streams.This species was quite commonin the oak-hickory woodlotsin centralOhio, but seems to have decreasedduring the last few years.In Wisconsinit is uncommonsouth of the coniferousforests, and probably absentfrom Illinois, according to Brownand Yeager (1945). The easternflying squirrel is widelydistributed, but has been reducedin numberby the removalof suitableden treesfrom many woodlots. The northern specieshas been less disturbed,and appearsto be abundantin some parts of the area consideredin the presentpaper. The woodchuckis widelydistributed, and is found in a wide varietyof habitats,from deep woods to cultivatedfields. We found it especiallyabun- dant in centralOhio, and numerousin southernMichigan. It is not, however, commonin southernWisconsin, and we were unable to securean adequate series fromthis region.In centralOhio, at least, this species has increased considerablyduring the past few years,partly as a result,perhaps, of lessened shooting. The chipmunkis found over much of the regionwith which we are con- cerned,but in manyareas it is not numerous.This is especiallytrue of central and westernOhio, where,when it does occur,it is uncommon.The destruction of suitablehabitat may in part be responsiblefor this. However,Aldo Leo- pold states (personalcommunication) that he has failedto observethis species in an area in centralWisconsin where he has made observationsfor several years,and wherethe habitatapparently is quite suitable.The least chipmunk is confinedto the northemedge of the regionunder consideration. Several questionsarise when one considersthe incidenceand distribution of squirrelhelminths over the area fromwhich our materialwas obtained. Unfortunately,an inadequate numberof host animals,a lack of intensive Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

740 THE AMERICAN MIDLAND NATURALIST 39 (3)

collectingin some areas, and unequal numbersof animals fromthe general areas involvedmake it impossibleto treatthese matters in detail. Futurework, c!one intensivelyon a local scale, as well as the examinationof many more host animals,will contributemuch to the understandingof the epidemiology of the sciuridhelminths found in thisregion. It is of interestto note that no helminthswere taken from31 specimens of 13-linedground squirrel taken in centralOhio, but 40 per cent of the 49 specimenscollected in Wisconsin were parasitizedby helminths.The few Franklin'sground squirrelsexamined from southern Wisconsin were lightly parasitized.McLeod (1933), who examined236 specimensof threespecies of the genus Citellus in Canada, also found relativelyfewer parasites in this species. The questionarises whethermammals collected from marginal range may show differencesin the extentto whichthey are parasitized,when compared withspecimens collected from areas representingmore nearlyoptimum conditions. It has been foundin some cases (Erickson,1944) that helminthparasites of a speciesincrease as the host approachesthe greatestdensity in the population cycle.We do not have sufficientsciurid material to allow any consideration of this; neitherdo the sciurids of this region show the spectacular fluctuationsin numberseen in certainother mammals. However, we have not found any definiteindication of this in otherhost animals.Of 345 meadow' voles,Microtus- p. pennsylvanicusOrd, examinedover a periodof 13 months fromone area, of which time 9 monthspreceded a typicalabrupt decrease in numberof animals,there was no evidenceof unusual parasitismwhen comparedwith about 100 voles collectedduring the previoustwo yearsfrom otherareas, duringpopulation lows. At the time of the populationdecrease, even animalsheavily infected with such helminthsas Protospirurasp. showed no evidence,as far as we could determine,of physicalinjury. A total of 21 foxesexamined during the unusuallyhigh populationden- sityof the winterof 1946-1947also showedno evidenceof an abnormaldegre! of parasitism.Of theseanimals, all but one wereparasitized by helminths;10 foxescontained Physaloptera sp. in the stomach,with an averageof 8.5 worms per animal; 6 animalswere infectedwith Taenia sp., with an averageof 4.6 wormsper animal; 12 animalswere infectedwith ascarids, with an averageof 21 wormsper animal. The part played by helminths,if any, in connection withcyclic fluctuations of the numbersof host animalsis certainlynot clear. The sciuridscollected in Wisconsinwere, both quantitativelyand qualita- tively,more heavilyparasitized than those collectedin Ohio and Michigan. Flowever,since equal numberswere not collectedeach year fromeach area, it is impossibleto determinethe amountof variationin the degreeof parasitism fromyear to year. It is of interestto note that certainof the helminths(Impalaia sp. and Mecistocirrussp.) recordedby Brownand Yeager (1945), fromsquirrels in Illinois,were not collectedby us. Certainother omissions from our list can be attributedin part to geographicaldistribution of the parasite,or its host. We observedno macroscopiclesions, clinical symptoms, or any injuryto Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

J948 RAUSCH ET AL.: HELMINTHS OF SCIURIDAE 741

the sciuridsexamined by us attrLbutableto helminthinfections, and we assume that the physicalcondition of the parasitizedanimals was normal. McLeod (1933) states that certainof the squirrelhelminths recorded by him often have a detrimentaleffect on the host,but our data do not supportthis. Con- currentstudies on other groups of mammals and birds definitelytend to substantiateour conclusion. The followingdata, while meager,are of intercst.Of 59 fox squirrels weighed,the 39 non-parasitizedspecimens averaged 702.1 grams,while the 20 parasitizedanimals averaged 743.5 grams.Most of thesespecimens were taken duringthe winterand earlyspring. One foxsquirrel, the most heavilyinfected individualencountered by us, containedthe followinghelminths: T. calcaratus, 1 specimen;C. bifurcatum,2 specimens;H. hassalli.438 specimens;Stron- gyloidessp., 33 specimens.It is of interestto note that this animal weighed 820.0 grams,and, as far as we could determine,was in excellentphysical con- clition. Of 27 specimensof 13-linedground squirrel weighed (males only,because of the greatdifference between the weightsof the sexes) 13 negativeanimals averaged159.3 grams,while 14 parasitizedanimals averaged 159.9 grams.In the case of the groundsquirrel, the animalswere all adults whichhad hiber- nated duringthe previouswinter, and whichwere taken in thz springbefore reproductionbegan. Species of helminthsare not consideredin the above examples.The slight d;fferencesin the averageweights probably would not have occurredif based on a largerseries of animals.These data are meantto serveonly as an indica- tion that we could observeno appreciabledifference in the physicalcondition of the parasitizedand non-parasitizedanimals, and we do not implythat the data have statisticalvalue. There can be no question that if young animals were exposed to heavy infections,at least with some of the trichostrongyles,fatalities would result. This has alreadybeen shownby Sarles (1932), using rabbits,for one of the species foundby us (T. calcaratus),and it is a generallyaccepted principle relatingto domesticanimals. Our data indicatethat in the North Central States,during the yearsand for the areas considered,the helminthswere only potential mechanismsof population control. The trichostrongylesrarely e3ceeded 10-15 specimensper host. However, Harkema (1936) conisistently found about 100 specimensof H. hassalli per animal in the southerngray squirrelin North Carolina. Some of these helminthsmay be more important in otherareas. Our resultsindicate that some of the internalparasitcs are a1le to survive the winterin at least some of the sciuridswhich hibernate (13-lined ground squirreland Franklin'sground squirrel), since severalof these were parasitized in the springwhen collected just afteremergence, and beforeany of the hciminthscould have maturedfrom newly-ingested larvae. This paper can only be considereda beginningin the study of the hel- minthsparasitic in squirrels.Future examinationsof more materialover a widerarea may changethe presentoutlook. Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

742 THE AMERICAN MIDLAND NATURALIST 9 (3)

ADDITIONAL OBSERVATIONS After this paper had been submittedfor publication,one of us (R. R.) had the opportunityto collectspecimens for parasitological study in Manitoba. Certainof the data resultingfrom these examinations are of interestin connectionwith what has alreadybeen presentedabove. Citellinemabifurcatum was foundto be a commonparasite of thenorthern red squirrel,Tamiasciurus h. hudsonicus(Erxleben), as farnorth as Garland, Manitoba. It was also recordedfrom Richardson's ground squirrel, Citellus richardsonii(Sabine) fromthis area and fromfarther south, at Ochre River, Manitoba. Thi, nematodewas recordedfrom the latter host by McLeod (1933). Seventeenspecimens of Trichurissp. were also takenfrom a Richardson's ground squirrelat Ochre River. This nematodewas not recordedby Dr. McLeod in his surveyof groundsquirrel parasites. While investigatingan outbreakof botulismin waterbirds at the south end of Lake Dauphin, near Ochre River,two specimensof C. richardsonii were collected. The burrowsof theseanimals were on the immediatemargin of a small stream,which ran throughan area whichhad been inundatedfor some months. One of these animals,about two-thirdsgrown, was found to be infectedwith Plagiorchisproximus Barker, 1915. Fourteentrematodes were taken fromthe small intestineof this animal. Plagiorchisproximus is a commonparasite of the muskrat,but apparentlyhas not previouslybeen recordedfrom Richardson's ground squirrel. Muskratsoccurred in the area fromwhich the infectedanimal was collected. We were fortutiatein being able to recordAscaris lumbricoidesfrom a fox squirrelcollected in St. Croix County,Wisconsin, on September9, 1947. A maturemale, measuring174 mm long, with over 50 pairs of precloacal papillae was taken from the small intestineof the animal, along with a smaller,immature specimen. This providedour firstopportunity to verifythe specificidentity of the Ascaris fromsquirrels of the North CentralStates. It would seem probable that this parasitewas of porcinerather than human origin,since hogs are abundant and frequentlyinfected with ascarids, over the region studied. WhetherAscaris columnariscan also infectsquirrels remains to be checked experimentally,or confirmedby fieldobservation. We wish to call to the attentionof those interestedin the epidemiology of Ascaris lumbricoidesthat we still lack evidencethat tree squirrelsever serve as reservoirsof infection. The small size of the lumen of the squirrel intestineas comparedwith the cross-sectionalarea of the adult wormwould seem to precludethe chances of fertilizedeggs being distributedon a very largescale. So far as we have been able to determine,there is no reportof A. lumbricoides ova beingfound in any sciurid. Baylis and Daubney (1922) failedto considerthe question,and specimensreported by Katz (1938), and Graham and Uhrich (1942) were immature. Ova were absentfrom an adult female collectedby Brown and Yeager (1945) (personal communicationfrom Dr. L. J.Thomas). Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

1948 RAUSCH ET AL.: HELMINTHS OF SCIURIDAE 743

ACKNOWLEDGEMENTS The writerswish to expresstheir appreciation of the generouscooperation extended by the ConservationDepartments of Michiganand Wisconsinin makingit possible to obtain many of the animals needed for this study.We are indebtedto Dr. C. E. Mickel, of the Universityof Minnesota,for the loan of the helminthsfrom Minnesota sciurids,and to Dr. J. S. Katz, formerlyof the Ohio Wildlife Research Unit, for permissionto use his unpublisheddata. Drs. I. 0. Buss and B. B. Morgan made help- ful suggestions for the preparation of the manuscript. The senior author feels especially indebted to Professor Aldo Leopold for a better understandingof some of the ecology involved in such an investigationas this. Several individuals aided very considerably in obtaining material for this and similar work with other groups; of these we are especially indebted to Messrs. L. H. Troesch, C. F. Troesch, Robert A. McCabe, L. L. Lemanski, R. C. Huebner, Wm. Huebner, R. W. Nero, N. C. Negus, W. H. Wilson, G. H. Breiding, W. C. Truax, D. W. Hayne, and B. P. Stollberg. Dr. J. A. McLeod kindly supplied type specimens of Rictulariacitelli, and Dr. E. W. Price made available the specimens of Rictularia collected by Dr. Katz in Ohio, and furnished valuable information on several points.

REFERENCES

ALLEN, D. L. 1943-Michigan fox squirrelmanagement. Michigan Dept. Cons. Game Div. Pub. 100, 404 pp. BOLE, B. P. AND MOULTHROP, P. N. 1942-The Ohio recentmammal collection in the Cleveland Museumof Natural History.Sci. Pub. Cleveland Mus. Nat. Hist. 5:83-181. BROWN, L. G. AND YEAGER, L. E. 1945-Fox squirrelsand gray squirrelsin Illinois. Bull. Ill. Nat. Hist. Survey23:449-536. BURT, W. H. 1946-The mammalsof Michigan.Univ. MichiganPress, 288 pp. CAMERON, T. 1932-On a new species of oxyuridfrom the gray squirrel in Scotland. Jour.Helminth. 10:29-32. CHIANDLER, A. C. 1941-The specificstatus of Moniliformis (Acanthocephala) of Texas rats,and a reviewof the species of thisgenus in the westernhemisphere. Jour.Parasitol. 27:241-244. 1942-Helminthsof tree squirrelsin southeastTexas. Ibid. 28:135-140. -- 1945-Trichuris species fromCalifornia rodents. Ibid. 31:284-286. - 1947-Notes on Moniliformisclarki in North American squirrels.Ibid. 33: 278-281. - AND RAUSCH, R. 1946-A studyof strigeidsfrom Michigan mammalswith commentson the classificationof mammalianstrigeids. Trans. Amer. Micr. Soc. 65:328-337. DALKE, P. D. 1942-The cottontailrabbits in Connecticut.Connecticut Pub. Doc. 47, Bull. 65, pp. 9-97. DARRAH, J. R. 1930-A new anoplocephalidcestode fromthe woodchuck,Marmota flaviventris.Trans. Amer. Micr. Soc. 49:252-257. DIKMANS, G. 1938-A considerationof the genusCitellinema with the descriptionof a new species,Citellinema columbianum. Proc. Hel. Soc. Wash. 5:55-58. DOBROVOLNY, C. G. AND HARBAUGH, M. J. 1934-Cysticercus fasciolaris fromthe red squirrel.Trans. Amer. Micr. Soc. 48:80-83. DOUTHIT'r, H. 1915-Studies on the cestode family Anoplocephalidae. Ill. Biol. Monogr. 1:1-96. ELTON, C., FORD, E. B., BAKER, J. R., AND GARDNER, A. D. 1931-The healthand parasites of a wild mouse population.Proc. Zool. Soc. London, 1931, pp. 657-721. Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

744 THE AMERICAN MIDLAND NATURALIST 39 (3)

ERICKSON, A. B. 1944-Helminth infectionsin relationto populationfluctuations in snowshoehares. J. Wildl. Man. 8:134-153. GRAHAM, E. AND UHR:CH, J. 1943-Animal parasites of the fox squirrel in southeast Kansas. Jour.Parasitol. 29:159-160. HALL, M. C. 1916-Nematode parasitesof mammalsof the ordersRodentia, Lago- morpha,and Hyracoidea. Proc. U. S. Nat. Mus. 50, pp. 1-258. 1919-The adult taenoidcestodes of dogs and cats and of relatedcarnivores .n NorthAmerica. Ibid. 55, pp. 1-94. HARKEMA, R. 1936-The parasitesof some North Carolina rodents.Ecol. Monogr. 6: 153-232. HUGHES, R. C. 1941-A key to the species of tapewormsin Hymenolepis.Trans. Amer. Micr. Soc. 60:378-414. JOYEUX, CH. AND BAER, J. G. 1945-Morphclogie, evolut:on ct pos'tion syst6matique de Catenotaeniapusilla (Goeze, 1782) Cestode parasite de Rongeurs. Rev. Suisse Zool. 52:13-51. KATZ, J. S. 1938-A survey of the parasites found in and on the fox squirrel (Sciurus nigerrufiiventer Geoffroy), and in the southerngray squirrel(Sciurus c. carolinensis Gmelin) in Ohio. Unpublishedthesis, Ohio State University. -- 1939-An annotatedbibliography of referencesconcerning parasites of squirrels. Ohio Coop. Wildl. Res. Unit, Release 131, 21 pp. Li, H. C. 1933-Parasitic nematodes,mainly from North China. Part III-Oxyuroidea. ChineseMed. Jour.47:1307-1325. LINSDALE, J. M. 1946-The California ground squirrel. University of California Press, 475 pp. LUCKER, J. T. 1943-A new trichostrongylidnematode from the stomachsof American squirrels.Jour. Wash. Acad. Sci. 33:75-79. MANTER, H. W. 1930-Two new nemotodesfrom the woodchuck,Marmota monax. Trans. Amer. Micr. Soc. 49:26-33. MARTIN, H. M. 1930-Notes on cestodelarvae. Part I. Taenia taeniaeformisin the fox squirrel.Part. III. The Multiceps serialis (Gervais) larvae in peritoneal cavityof the westernfox squirrel(Sciurus nigerrufiventer Geoffroy). Jour. A. V. M. A. n.s. 29:804-810. McCoy, G. W. 1911-A microfilaria(Microfilaria rosenaui n. sp.) fromthe Califor- nia groundsquirrel (Citellus beecheyi).Parasitol. 4:220-221. MCINTOSH, A. 1934-Two new species of trematodes,Scaphiostomum pancreaticum and Postharmostomumlaruei fromthe chipmunk.Proc. Hel. Soc. Wash. 1:2-3. - 1937-A new trematode,Postharmostomum noveboracensis n. sp. froma chipmunk.Ibid. 4:23-24. - AND MCINTOSH, G. E. 1934-A new trematode, Notocolylus hassalli n. sp., froma meadowmouse. Ibid. 1 :36-37. McLEOD, J. A. 1933-A parasitologicalsurvey of the genus Citellus in Manitoba. Canad. Jour.Res. 9:108-127. MILLER, H. M. AND GARDINER, M. L. 1934-Further studies on passive immunityto a metazoanparasite, Cs -icercusfasciolaris. Amer. Jour.Hyg. 21:424-431. MORGAN, B. B. 1943-The Physaloptera(Nematoda) of rodents.The Wasmann Col- lector.5:99-107. PRICE, E. W. 1928-Two new nematodeworms from rodents. Proc. U. S. Nat. Mus. 74, art. 4, pp. 1-5. RANKIN, J. S. 1945-Ecology of the helminth parasites of small mammals collected from NorthrupCanyon, Upper Grand Coulee, Washington.The Murrelet 26:11-14. Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

1948 RAUSCH ET AL.: HELMINTHS OF SCIURIDAE 745

1946-Helminth parasites of birds and mammals in westernMassachusetts. Amer. Midl. Nat. 35:756-768. RAUSCH, R. 1946-New recordsof Macracanlhorhynchus hirudinaceusin Sciuridae. Jour.Parasitol. 32:94. I1947-A ndrya sciu1'i n. sp., a cestode fromthe northernflying squirrel. Ibid. 33:3 16-318. - AND TINER, J. D. 1946-Obeliscoides cuniculi fromthe woodchuckin Ohio and Michigan.Jour. Mammal. 27:177-178. REIBER, R. J. AND BYRD,E. E. 1942-Some nematodesfrom mammals of ReelfootLake in Tennessee.Jour. Tenn. Acad. Sci. 17:78-89. SANDGROUND, J. H. 1935-Spirura michiganensis and Rictularia halli, new parasitic nematodesfrom Eutamias strialus lysleri. Trans. Amer.Micr.Soc. 54:155-166. SARLES, M. P. 1932-Fatal infectionsof Trichostrongplus calcaratus in rabbits.Jour. Parasitol. 19:157. SCHWARTZ, B. 1927-The life historyof tapewormsof the genusMesocestoides. Sci- ence 66, no. 1696:17-18. 1928-The occurrenceof larval tapewormsin the liver, lungs,spleen, kidneys, omentum,and heartof the squirrel(Sciurus carolinensis).Hel. Soc. Wash. in Jour.Parasitol. 15:67. SLEGGS, G. F. 1925-A strongyloidnematode, Warrenius bifurcatus, n. sp. fromthe Richardsonground squirrel. Parasitology 17:410-416. 'TRAVASSOS, L. 1937-Revisao da familia TrichostrongylidaeLeiper, 1912. Monogr. Inst. Osw. Cruz 1, 512 pp., 295 plates. (containshost-parasite list.) 'IWICHELL, A. R. 1939-Notes on the southernwoodchuck in Missouri.Jour. Mammal. 20:71 -74. W1ALLACE, F. G. 1942-The stomachworm Obeliscoidescuniculi, in the woodchuck. Jour.Wildi. Man. 6:92. WELLMAN, C. AND WHERRY, W. B. 1910-Some new internalparasites of the Califor- nia groundsquirrel (Olospermophilus beecheyi). Parasitol. 3:417-422.

TABLE 1.-Animals examinedby the writers.

No. ex- No. in- Host amined Parasite fected

Sciurus niger rufiventer-94 Taenia taeniaformis - 2 Taenia pisiformis- .1 Hpmenolepisdiminuta -- 2 Catenofaeniapusilla -1 Mesocestoideslatus -1

Rictularia sp. -2 Ascaris sp.- .---2 Ciellinema bifurcalum-21 Heligmodendriumhassalli -. - 5 Trichostrongpluscalcaratus - 2 Boehmiella wilsoni - 2 Strongploidessp - . --2 Enterobiussciuri . --4

Macracanthorh_nchushirudinaceus -2 Sciurus c. carolinensis-.- . 6 00 Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

746 THIE AMERICAN MIDLAND NATURALIST 39 (3)

TABLE 1 -(Continued.)

No. ex- No. in- Host amined Parasite fected

Sciuruscarolinensis leucotis - 27 Rictulariahalli - - 3 Ciellinemabifurcatum - 8 Heligmodendriumhassalli - 5 Trichostrongyluscalcaratus - 3 Boehmiellawilsoni - - 3 Strongyloidessp. - - 4 Physaloplerasp. - - Capillariasp. - - 2 Tamiasciurushudsonicus - 19 Fibricolanana -1 Unidentifiedcestode -1 Rictulariasp -1 Ascarissp. -1 Citellinemabifurcatum - 5 Heligmodendriumhassalli -1 Strongyloidessp.-1 Tamias striatus-43 Scaphiostomumpancreaticum - 3 Hymenolepisdiminuta -1 Hymenolepissp -1 Rictulariahalli -9 Trichostrongylussp.-1 Spiruramichiganensis - 6 Trichurissp. -2 Capillariasp -9 Glaucomysv. volans-20 Citellinemabifurcalum -1 Enterobiussciuri -12 Capillariasp. -6 Glaucomyssabrinus macrotis - 5 Catenotaeniapusilla -- 3 Andryasciuri -2 Citellinemabifurcatum - 2 Syphaciathompsoni -- 5 Citellust. tridecemlineatus 89 Hymenolepisdiminuta - 13 Cysticercussp-- 1 Rictulariacitelli - 9 Phypalopterasp -2 Citellusfranklini -10 Hymenolepisdiminuta -1 Physalopterasp. -1 Capillariasp- - 1 Marmotamonax -21 Quinqueserialishassalli -1 Citellinemabifurcatum -1 Obeliscoidescuniculi -- 8 Citellinamarmotae . 2 Rausch & Tiner in American Midland Naturalist (May 1948) v. 39, no. 3. Copyright 1948, University of Notre Dame. Used by permission.

1948 RAUSCH ET AL.: HELMINTHS OF SCIURIDAE 747

TABLE 2.-Animals examined by Katz.

No. ex- No. in- Host amined Parasite fected

Sciurus nigerrufiventer -16 Hymenolepissp. -1

Citellinemabifurcatum - 4 Heligmodendriumhassalli - 2 Rictularia sp.-1 Capillaria sp-- 1

Sciurus c. carolinensis-72 Catenoiaenia sp. -4 Hymenolepissp. -4

Rictularia sp -7 Ascaris lumbricoides-1 Citellinemabifurcatum -25 Heligomodendriumhassalli - 50 Capillaria sp.-1

TABLE 3.-Helminths fromMinnesota collection.

No. ex-* No. in- Host amined Parasite fected

Sciurus niger rufiventer-3 Citellinemabifurcalum -1 Boehmiella wilsoni-.1 Unidentifiedtrichostrongyle -1 Sciurus carolineniishypophaeus - 1 Citellinemabifurcatum -1 Unidentifiedtrichostrongyie -1 Citellus t. tridecemlineatus- 1 Hymenolepisdiminuta -1 Rictularia citelli-1 Spirura infundibuliformis-1 Physalopterasp. -1

Marmota monax-3 Citellina marmotae - 2 Unidentifiedoxyurid -1 Eutamias minimusjacksoni - 11 Rictulariasp -1 Citellinemabifurcatum - 2 Syphacia sp -8

Moniliformissp. - 1

6 The numberof negativeanimals examined is unknown.