ANATOMY OF THE MIDDLE EAR REGION OF THE AVIAN SKULL: SPHENISCIFORMES

EDWARD SAIFF

WHEN I reviewedthe literature on the middle ear regionof birds (Saiff 1974), it became obvious that few anatomical studies have been made on this regionin birds, penguinsin particular. Watson's (1883) report on the anatomyof the Sphenisciformeslacks any detailson the middleear. Walker (1888) studiedquadrate morphology in a large variety of birds includingSphenisciformes. Pycraft (1898) describedthe skullof penguins but passedover the middle ear region save for a few brief statementsre- gardingthe quadrate,basitemporal platform, eustachiantube, and the trigeminalforamen. Shufeldt (1901) also failed to go into detailsof the middleear regionin his osteologicalstudy of the penguins.More recently, in a study of the evolution of penguins,Simpson (1946) describedthe skull of Paraptenodytesantarcticus, a fossilpenguin. This studytheorized a close relationship between the penguins and the Procellariiformes. Crompton (1953) made a further study on penguinsand did an extensive developmentalstudy of the chondrocranium.An analysisof middle ear anatomy of Procellariiformes,including a glossaryof avian middle ear characters,appears in Saiff (1974). Recently Frost et al. (1975) de- scribedthe circulatory systemin the head o/ Spheniscusdemersus in an effort to describeheat-exchange systems in penguins. Obviouslacunae exist in the studyof the middleear of birds,including Sphenisciformes.This study describesthe anatomyof the middle ear and basicraniaof the Sphenisciformesand where possiblemakes com- parisonswith Procellariiformes.

MATERIALS AND METItODS

This study is based on an analysis of charactersof specimensborrowed from the Bird Department of the American Museum of Natural History. Peters (1931) was used as the basis for the genericclassification and Wetmore (1930) for the higher taxa. I studied the following specimens: dried skull: Aptenodytes/orsteri AMNH 3745. A. patagonicaAMNH 1623, 2611, 3139, 4630, 4383, 4382. Eudyptes chrysolophus AMNH 5974. E. crestatusAMNH 3854, 5398, 5972. E. pachyrhynchusAMNH no number. E. schlegeliAMNH 5399. Eudyptula rainor AMNH 5314, 5620, 6257. Megadyptesantipodes AMNH 5613, 5615. Pygoscelisadeliae AMNH 5041. P. papua A.MNIt 3196, 4361, 5373, 5766, 5973. Spheniscusderaersus AMNH 1625, 1310, 3875, 4042, 4069, 4942. S. huraboldtiAMNH 2768, 4920, 4921. S. raendiculusAMNH 3648, 3772. Dissected: S. deraersus AMNH 4548.

749 The Auk 93: 749-759. October 1976 750 EDWARDSA• [Auk, Vol. 93

ANATOMICAL DESCRIPTIONS

EXTERNAL.--Theexternal auditory meatusis on the same horizontal plane as the gape. The meatus lies on the border of a white band of feathersthat runs first over and then behind the eye and a dark feather patch that extendsposterior to the gape onto the throa region. The feathers that cover the external meatus grow only from its anterior rim. The meatus ranges between 2.4 to 3.5 mm tall and 1.9 to 2.1 mm wide (2 ears). The rim of the meatusdoes not appearto be sopliable as to close completely. The external auditory canal is directed posteroventrally.No ridges appear on the inner membranouslining of the canal. Ridges do appear with somedegree of consistencyin Procellariiformes(Saiff 1974) although the presenceor absenceof suchridges may be an effect of preservation. Upon removal of the m. depressormandibulac, the oater membrane coveringof the external auditory canal becomesvisible and when this is dissectedopen the tympanicmembrane comes into view. The tympanic membrane is roughly circular in shape, mildly protubcrant, and faces posterolaterad.It is composedof a tough, thick outer layer that is quite elastic and a thinner but equally tough inner layer. The outer layer of the tympanic membrane is a continuation of the lining of the external auditory canal while the inner layer is continuouswith the epithelium lining the middle ear cavity. The inferior processof the extra-columella, coveredby its ligament,lies embeddedwithin the inner tympaniclayer. Here the tympanic membrane is thickened. The tympanic membrane separatesthe externalauditory canal from the middle ear cavity. ANATOMY O1' THE MIDDLE EAR REGION. The middle ear of all six generaof penguinsis characterizedby a conicaltympanic cavity as seen in Fig. 1 that opensto the rear of the skull medial to the quadrate. Watson (1883) clearly figured this region but did not label it. The dorsal,ventral, and anteriorwall of the tympaniccavity is a curvedplate of bone that extendslaterally to touch the rear of the dorsalend of the quadrate; the ventral edgeof this plate is bent backwardhorizontally to form, alongwith a lateral extensionof the basitemporalplate, the ventral wall of the tympanic cavity. The tympanicmembrane (seen dried in placein someskulls as well as in situ in AMNH 4548) is stretchedacross the rear apertureof the tympanic cavityfrom the metoticprocess to the quadrate.On the medialwall of the tympanic cavity is the fenestraovalis, posteriorto which is a pneumatic foramen. Ventral to thesetwo structuresis the recessusscalae tympani. The seventh nerve foramen varies among the specimensexamined. A facial foramenopening within the tympaniccavity is lackingin Eudyptes, October1976] PenguinMiddle Ear Region 751 VlI FR AQF U/TRC I / / /

•X !..... H

PA ET BP MP CF M Fig. 1. Spi•eniscusdemersus (AMNH 4042) obliqueventral view of the left middle ear regionwith quadrateremoved: AQF, anteriorquadrate facet; BP, basitemporal platform;C, columella;CF, carotidforamen; ET, entranceto eustachiancanal; FP, foramenprooticum; H, hypoglossalforamen; IX, glossopharyngealforamen; •I, metoticprocess; MP, mammillaryprocess of basitemporalplatform; OF, foramenfor occipitalvein; P, pneumaticforamen; PA, foramenfor palatineartery; SF, stapedial arterialforamen; TC, tympaniccavity; UTR, uppertympanic recess; VCL, exit point from skullof venacapiris lateralis; VIIp, foramenfor palatinebranch of facialnerve; X, vagal foramen.

Eudyptula,Megadyptes, and Spheniscus. Crompton (1953) studiedthe de- velopmentalprocess involved in this arrangementin Spheniscus.The palatinenerve enters the carotidcanal through a foramenon its dorso- medialsurface in orderto runforward along with the carotid artery. The sectionof the carotidcanal where the palatinenerve and carotidartery traveltogether represents the parabasalcanal. At the anterolateraledge of the parabasalcanal is a foramen for the forward continuationof the palatinenerve. Just anteriorto this palatinenerve foramen is a larger foramenfor the palatine artery. The hyomandibularbranch of the facial nerveexits from a foramenlocated posterodorsal and lateral to 752 Et)w^a• S^•v [Auk, Vol. 93 the fenestraovalis and then leavesthe middle ear regionwith the stapedial artery throughthe stapedialarterial foramen. One specimenof Eudyptula (AMNH 5314) I examinedhad a foramenonly on the right side of the inner wall of the tympanic cavity. This foramenis coveredover by a membraneand is probably pneumatic. Aptenodytes has a facial foramen. Dorsal and lateral to the facial foramen is an overhang of bone that is a forward continuation of the lateral wall of a canal that curvesposterodorsally above the fenestra ovalis and opensposteriorly into the middle ear cavity. The posterior openingis directed toward the foramen housingthe stapedialartery. It seemsreasonable to assumethat the hyomandibularnerve travels within this bony canal up to the stapedialcanal and leavesthe middle ear region via the stapedialcanal and the stapedial arterial foramen. Anteroventral to the facial foramena foramenenters the carotidcanal from the tympanic cavity. Presumably the palatine nerve travels along the wall of the tympanic cavity to enter the carotid canal through this foramen. The presenceof a facial foramen opening into the middle ear of Pygosceliscannot be determined without a dissection. Anterolateral to the fenestraovalis in Pygoscelisare two fossaeseparated by a vertical ridge of bone. On this ridge is a foramenthat is patent only on the left side in one of the specimensexamined here (AMNH 5766) and in none of the others. It is not possibleto tell whether this foramen is for the facial nerve, and if so, for which branch. It is doubtful, though,that the palatinebranch would exit from this foramen. If it did, it wouldhave to travel posteriorlyfor almost the entire length of the tympanic cavity in order to enter the carotid canal as there is no foramen that leads into the carotid canal from the tympaniccavity as is presentin Aptenodytes. All speciesexamined had a bony canal for the stapedial artery dorsal to the columella,deep to the tympanic cavity. Posteriorto entry into the middle ear, the stapedial canal runs medial to a vertical bar of bone (the lateral edge of the metotic process) connectingthe rear of the paroccipitalprocess to the rear of the basitemporalplatform. Running anteriorly in the ventrolateralportion of the tympanic cavity are two bony canals: a lateral canal for the eustachiantube, and a more dorsomedialcarotid canal. These two canals are separatedby a thin plate of bone referred to by Pycraft (1898) as a downgrowthfrom the alisphenoidwing of the parasphenoid.Anteriorly, the tympaniccavity is blind. The blind area presumablyrepresents the presphenoidsinus of several Procellariiformes,Pelecaniformes, and Ciconiiformes(Salff 1973). In all penguinsexamined the carotid artery enters the carotid canal throughthe carotidforamen, which is locatedventromedial to the tympanic October 1976] Penguin Middle Ear Region 753 cavity. The carotidartery is neverexposed within the tympaniccavity. Just beforeentering the middleear, the carotidartery givesoff a dorsal branch,the stapedialartery, which lies dorsalto the columella. Deep to the stapedialartery, and alsodorsal to the columellais the vena capitis lateralis. Togetherthe stapedialartery complexof vesselsand that of the vena capitis lateralis form arete mirabile locatedlateral to the foramen prooticum. The vena capitis lateralis leaves the middle ear through a notch in the anterodorsaledge of the tympanic cavity just deep to the quadrate. In Megadyptesand Aptenodytesa large dorsallydirected pneumatic foramen enters into the braincaseposterior to the dorsal rim of the tympaniccavity and deep to the point of entry of the stapedialartery into the middle ear. None of the other generahas such an opening. All forms have a foramenjust anterior to the articulatorysurface for the headof the quadratein the paroccipitalprocess. This foramentakes the form of an elongateslit and appearsto be the true upper tympanic recess.Anterior to the upper tympanicrecess is an openingin much the positionof the uppertympanic recess of the Diomedeidaeand Procellariidae (Saiff 1974); this openingin penguinsenters the brain cavity and appears to bepneumatic. In the Procellariiformes,Pelecaniformes, Sphenisciformes, and Ciconiiformes,the true upper tympanicrecess is separatedfrom the brain cavity by an imperforatewall of bone (Saiff 1973). Ventral to the perforationinto the brain cavity and anterior to the tympaniccavity is the foramenprooticum. Pycraft (1898) describedthe morphologyof the foramenprooticum as well as that of the pneumatic foramen dorsal to it. At the base of the skull posterior to the tympanic cavity are the glossopharyngeal,vagal, and hypoglossal foramina, which Crompton (1953) described.The glossopharyngealand vagal foraminaare located in the metotic process.Pycraft (1898) describedthe posterioraspect of the skull and the basitemporalplatform, the formerbeing variable among the generawhile the latter is constant.The basitemporalplatform as seenfrom belowis triangularand concave.The eustachiantubes make the lateral edgescurl ventrally,hence the concavity.At the rear of the basitemporal platform on each side is a weak mamillary process."In all generabut Spheniscusthere is a well-markedprecondylar fossa" (Pycraft 1898). In all respects,save the mamillaryprocess, the basitemporalplatform (Table 1) of Sphenisciformesis very similarto that of Procellariiformes,especially Diomedea (Saiff 1974). In all the generaof penguinsthe eustachiantubes are at least partly coveredby bone. In Eudyptes,Spheniscus, and Megadyptesthe bony coveringextends to near the anteriorend of the basitemporalplatform 754 EDWARDSAIFF [Auk, Vol. 93 October 1976] Penguin Middle Ear Region 755 while in Eudyptula, Aptenodytes,and Pygoscelisit coversonly the pos- terior half of the eustachian tube. QUADRATEAND ITS RELATIONTO THE MIDDLEEAR.--Pycraft (1898) describedthe quadrate of the penguins. The quadrate articulatesnear the anteriorend of the paroccipitalprocess by two heads.The articulation is strengthenedby a broad ligamentconnecting the paroccipitalprocess and the Jarera]edge of the curvedarticu]atory surface of the outermost headof the quadrate. A portionof this ligamentextends to the dorsalmost lip of the tympanic cavity. The vena capiris ]ateralis runs just deep to this portionof the ligament. The angieof articulationis approximately at right angleswith the long axis of the head. Posteriorto the point of articulationa ventral curveof the paroccipitalprocess extends about halfway down the ]eve] of the tympanic cavity. The quadrateitself exhibitsa deep capitu]argroove separating the prootic and squamosa]-opisthoticarticu]ar headswith the paroccipital process.The facets for thesearticu]ar headsin the paroccipitalprocess are quite distinct from each other. A line drawn through these facets intersectsthe long axis of the skull at app,roximate]ya 45-degreeangie. The uppertympanic recess is locatedanterior to thesetwo facets. The penguinsshow someslight variability with regard to the orbital process. That of Eudyptula,Eudyptes, and Spheniscusis curvedslightly upward with the superiorborder sharper than the inferior. In Pygoscelisthe orbital processis similar in shape but longer. In Aptenodytesand Megadyptesthe orbital processis taller than thosedescribed above al- thoughof the sameapproximate length as the Eudyptula grouping. The pterygoidarticulatory surface lies ventral and medialto the orbital process.The quadrato-jugalarticulatory surfaceis at the base of the quadrateshaft on its lateral aspectjust dorsalto the mandibulararticu- latory surface.Little variability amongthe severalgenera of Spheniscidae exists in the mandibular articulatory surface. Pycraft (1898) failed to describethis portion of the quadrate. The penguin has a shallow trochleargroove separating the inner and outer condylarpairs and no grooveto distinguishthe two condylesof the outer condylarpair from each other save for a shallowdepression in Eudyptula and Megadyptes. The two condylesof the inner condylarpair are distinctfrom eachother but the groove separatingthem is much shallowerthan in Diomedea (Saiff 1974). The quadrateof penguinslacks a pneumaticforamen.

DISCUSSION

PRESPI-IENOID SINus.•The anatomical literature makes little mention of this structure. Watson (1883) figured it in his description of the 756 Et)w^,al>S^•w [Auk, Vol. 93 osteologyof the penguinsand Pycraft (1898) madesome mention of it. There seemslittle doubt that the presphenoidsinus is pneumatic. In the Sphenisciformesit is shallow,poorly developed, and directedantero- medially. Its lateral wall fusesventrally with the free edge of the basitemporalplatform and is in closecontact posteriorly with the quadrate shaft. The downward extensionoffers lateral protection to the carotid artery and eustachiantube (Table 1). Suchprotection is absentin the Diomedeidaealthough it is presentto varying degreesin other Procel- lariiformes(Saiff 1974). Only in Daption capensisamong the Procel- lariiformesdoes the hind portion of the lateral wall of the presphenoid sinus come into contact with the quadrate, a condition also seen in penguins. Uvw• T¾•rVA•iC R•c•ss.--The positionof the entranceto the upper tympanicrecess with respectto the facetsfor the headof the quadrate has beenused as a taxonomiccharacter in birds (Lowe 1926, Saiff 1974). All the Sphenisciformeshave a small, slit-shapedentrance to the upper tympanic recessthat lies anterior to the paired quadrate facets. In the Diomedeidae,Pelecanoididae, and Procellariidaeof the Procellarii- formesthe entranceis much larger than in the penguinsbut the position with respectto the quadratefacets is the same.The entranceto the upper tympanicrecess in the Hydrobatidaeof the Procellariiformesis small and locatedbetween the quadratefacets and not anteriorto them(Saiff 1974). FACIALFo•AMEN.--Aptenodytes is the only Sphenisciformthat has a facial foramenopening within the middle ear. The palatine ramuscon- tinues forward to the parabasalcanal; the hyomandibularramus passes througha foramenin the ventral wall of a canal that continuespostero- dorsallyto join the stapedialarterial canal. Presumablythe hyomandibular nervepasses into the stapedialarterial canal and then leavesthe middle ear throughthe stapedialarterial foramen. Crompton(1953) gave an accountof the early developmentof the chondrocraniumof Spheniscus demersusincluding a descriptionwith figuresof the ontogenyof the facial foramen,its subsequentclosing over, and the path ultimately taken by the facial nerve. ME:ro:rxcP•ocEss.--Crompton (1953) discussedmuch of the literature concernedwith this structure,as well as its developmentin Spheniscus demersus.All the Sphenisciformeshave a strong metotic processper- foratedby vascularforamina as well as foraminafor the glossopharyngeal, vagus,and hypoglossalnerves. In many respectsthe metoticprocess of thepenguins is markedlydifferent from that of theProcellariiformes (Saiff 1974). The metoticprocess of the Diomedeidaeis weakand lackseven a separateglossopharyngeal foramen. Also lackingare vascularforamina as in all the ProcellariiformesI previouslyexamined (Saiff 1974). October 1976] Penguin Middle Ear Region 757

ENTRY or CIRCULATIONINTO THE HEAD.--In the singlespecimen that was dissected,the relativeposition of the foramenmagnum with respectto the basitempora]platform showsthat the carotid artery and vena capiris ]atera]is do not have to bend to enter the head from the neck. Frost eta]. (1975) figure this in their recentpaper. This is a different arrangement from that in the Proce]]ariiformes(Saiff 1974). Even so, the vena capiris ]atera]is,stapedia] artery, and carotid artery of penguinspass through foraminain the metotic process,as in the Pe]acaniformes(Saiff 1973), rather than entering the middle ear in front of the metotic processas in the Proce]]ariiformes. MIDDLEEAU ARTERIES.--Thecarotid artery of the Sphenisciformesis completelyencased in a bony tunnel as it traversesthe middle ear. The stapedia]artery is alsoprotected on its lateral, roedial,and ventral sides. This protectionresults from the closeproximity of the quadrate and the lateral wail of the presphenoidsinus, which form a canalfor the stapedial artery. RETE MII•mILE.--In this study I dissectedonly a singlespecimen, and it had arete mirabile. Frost et al. (1975) also found arete mirabile in his dissectionsof S. demersus.S aiff (1973) describedthe presenceor absence of the structure in several other birds. As far as can be determined no physiologicalor behavioralfeature distinguishesthe forms possessing arete mirabilefrom thosethat lack one. Frost et al. (1975) discussedthe literature concerningretia mirabile as heat-exchangesystems. Certainly further studies involving dissectionsof more speciesare in order. EUSTACI-IIANTu•E.--This structure runs from the anteroventral region of the middle ear cavity to a medianopening in the rear of the palate, which it shares with its fellow from the other side of the head. The eustachiantube of the Sphenisciformesruns along the edge of the basi- temporal platform in a long canal that is at least partly protected by boneon all sidesin all genera. Qu•ml•TE.--Pycraft (1898) and Shufeldt (1901) describedquadrate structurein penguins.The sphenisciformquadrate is at right angleswith respectto the long axis of the skull (in lateral view), and an extensive capitular groove separatesthe paired condylesof the quadrate head. Dorsal to the capitular groovein the paroccipitalprocess a wide ridge of bone separatesthe facets for the quadrate head. These facets are perpendicularto the long axis of the skull. The upper tympanic recessis just anteriorto a line drawn betweenthe two facets. The orbital processof the severalspecies of penguinsvaries a bit but noneis significantlydifferent from that of the albatross(Saiff 1973). The arrangementof condylesof the mandibulararticulatory surfaceis also as in Diomedea (Saiff 1973), but the condylesof the penguinsare 758 Eow^•o S^rvv [Auk, Vol. 93 separatedby groovesthat are quite a bit shallowerand lesselongated than in the albatross.

CONCLUSIONS Althougha numberof authors,notably Murphy (1936), Murphy and Harper (1921), and Simpson(1946), have held the Sphenisciformesto be closelyrelated to the Procellariiformes,the middle ear givesno confirma- tion of it. Indeed, a cursoryexamination of five of the characterscovered in this work indicatesthat the middle ear of the gull, Larus argentatus, comes closer to the penguins than do those of the Diomedeidae or Procellariidae(Table 1). At the same time severalother characteristics are sharedby severalProcellariiformes and Sphenisciformes,such as ridges on the walls of the externalauditory canal, the presenceof arete mirabile, basitemporalplatform save the mammillaryprocess, and positionof upper tympanic recesswith respectto the quadrate facets. Wetmore (1930), Peters (1931), Murphy (1936), Simpson(1946), and Storer (1960, 1971) agree that the Spheniscidaeare composedof six genera, which my data confirm. The Sphenisciformesare easily distin- guishedfrom the Procellariiformes(Saiff 1973, 1974) and the Pelecani- formesand Ciconiiformes(Saiff 1973) by the penguins'wide presphenoid sinus,which has a lateral wall that fusesto the basitemporalplatform and is in closecontact with the medial edgeof the quadrateshaft, thoughthe presphenoidsinus extendsonly a short distancerostrad. All the penguinssave Aptenodyteslack a facial foramen. Perhapsthis is another characterindicating the primitivenessof that genusamong the Sphenisciformes.Many workers have studied the ancestry of extant penguinsand do not agreeon which genusis the most primitive and nearest to the ancestral form. Pycraft (1898) favored Eudyptula based on his osteologicalanalysis of temporal fossae,upper jaw, quadratojugalbar, sternum and pectoral limb, while Wilson (1907), based on color char- actersof the head plumage,believed Aptenodytes closest to the primitive form.

ACKNOWLEDGMENTS

Much of the data presented here was part of a thesis at Rutgers University done under the supervisionof Samuel B. McDowell. Iohn Maroney, Charles O'Brien, Alan O'Conne]], Dean Amadon, Waiter Bock, and Wesley Lanyon kindly allowed me to study specimens under their care. The Ramapo College Graphics Center prepared Fig. 1.

SUMMARY The osteologyand soft anatomy of the middle ear regionof the skull are describedfor the Sphenisciformeswith particularemphasis on the foramina for nervesand blood vessels.Also discussedis the morphologyof the October 1976] Penguin Middle l•ar Region 759 basicraniumand the quadrate. Comparativeanalysis of the characters are usedto assesstaxonomic conclusions. Little supportis addedto the theorythat the penguinsare closelyrelated to the Procellariiformes. The paper is part of a seriesthat attemptsto allow an assessmentof evolutionaryrelationships within the Avesbased on the anatomyof the middle ear region.

CRO2VIPTOl•,A. W. 1953. The developmentof the chondrocraniumof Spheniscus demersuswith specialreference to the columellaauris of birds. Acta Zool. 34: 71-146. FROST,P. G. H., W. R. Sx•mmx•D,A•m P. J. Gm•E•WOOD.1975. Arterio-venous heat exchangesystems in the JackassPenguin Spheniscusdemersus. J. Zool. London 175: 231-241. LOWE, P. 1926. More notes on the quadrate as a factor in avian classification. Ibis 12, 2nd Set.: 152-189. MvRPa¾, R. C. 1936. Oceanicbirds of South America. New York, Amer. Mus. Nat. Hist. MvRPa¾, R. C., A•rDF. HARPER. 1921. A review of the diving petrels. Bull. Amer. Mus. Nat. Hist. 44: 495-554. P•T•RS, J. L. 1931. Check-list of the birds of the world, vol. 1. Cambridge, Massachusetts,Harvard Univ. Press. P¾CP,A•?T, W. P. 1898. Contributions to the osteology of birds. Part II, Impennes. Proc. Zool. Soc. London 1898: 958-989. SAtin?,E.I. 1973. The middle ear of the skull of the avian orders Procellariiformes, Pelecaniformes,Sphenisciformes, and Ciconiiformes. Unpublished Ph.D. disserta- tion, New Brunswick, New Jersey, Rutgers Univ. S^rvF, E.I. 1974. Anatomy of the middle ear of birds, The Procellariiformes. Zool. J. Linnean Soc. London 54: 213-240. S•rm?•DT, R.W. 1901. Osteologyof the penguins. J. Anat. Physiol. 15: 39•405. Sx•xPSO•r,G. G. 1946. Fossil penguins. Bull. Amer. Mus. Nat. Hist. 87: 1-99. STOR•R, R. W. 1960. A classification of birds. Pp. 57-93 in Biology and com- parative physiologyof birds, vol. 1 (A. J. Marshall, Ed.). New York, Academic Press. STOR•R,R. W. 1971. Classification of birds. Pp. 1-18 in Avian biology, vol. ! (D. S. Farner and J. R. King, Eds.). New York, Academic Press, WAlKeR, M. L. 1888. On the form of the quadrate bone in birds. Studies Mus. Zool. Univ. Coil. Dundee. 1888: 1-18. WATSO•r,M. 1883. Report on the anatomy of the Spheniscidaecollected by H.M.S. Challenger during the years 1873-1876. Report of the scientific results of the H.M.S. Challenger 1873-76. Zoology 7: 1-243. WET:VroR•,A. 1930. A systematic classificationfor the birds of the world. Proc. U.S. Natl. Mus. 76: 1-8. Wrr•so•r, E. 1907. Aves. Brit. Natl. Antarct. Exped. 1901-1904. 2, Zool. part 2: 1-121.

Schoolo/ Theoreticaland Applied Science,Ramapo Collegeo/ New Jersey,Mahwah, New Jersey07430. Accepted15 April 1975.