Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ANIMAL INDUSTRY—Bulletin No. 79. D. E. SALMON, D. V. M., Chief of Bureau. THE DETERMINATION OF GENERIC TYPES. AND A LIST OF ROUNDWORM GENERA, WITH THEIR ORIGINAL AND TYPE SPECIES. CH. WARDELL STILES, Ph. D., Zoologist, U. S. Public Health and Marine-Hospital Service; Consulting Zoologist, Bureau of Animal Industry, ALBERT HASSALL, M. R. C. V. S., Assistant, in Zoology, Bureau of Animal Industry. WASHINGTON: GOVERNMENT PRINTING OFFICE, I9O5. LETTER OF TRANSMITTAL U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ANIMAL INDUSTRY, Washington, D. C, July 00, 1905. SIR: I have the honor to transmit herewith for publication a techni- cal manuscript entitled "The Determination of Generic Types, and a List of Round worm Genera, with their Original and Type Species", prepared by Doctors Stiles and Hassall. Medical, veterinary, and zoological literature has been inconven- ienced to no slight degree by changes in the technical names, due to a failure on the part of authors to designate type species for their genera. The present paper is prepared in tne hope of definitely fixing the types for the round worm genera, especially for those of impor- tance in human and comparative medicine, so that confusion in the future may be reduced. The adoption of a rule by the International Commission on Zoolog- ical Nomenclature to the effect that no new generic name may demand recognition in the future unless its author definitely fixes the type at its original publication is worthy of serious consideration, as such a rule would greatly simplify work. Respectfully, D. E. SALMON, Chief of Bureau. Hon. JAMES WILSON, Secretary of Agriculture. 3 TABLE OF CONTENTS. Page. Summary 7 Part I. Principles involved in designating the types of genera of parasites 10-80 Introduction 10 Genera other than nematodes included in this paper 11 Types designated or not designated 11 Division of work 12 Homonyms 12 Historical review of type designation 12 The principle of generic types foreshadowed by Linnaeus, 1751 12 The British Association (Stricklandian) Code 13 TheDallCode, 1877 15 The American Ornithologists' Union Code, 1886, 1892 17 The Code of the German Zoological Society, 1894 18 TheMerton Rules, 1896 18 Gill, 1896 20 Durrant, 1898 21 Code of Botanical Nomenclature, A. A. A. S., 1904 22 The International Code of Zoological Nomenclature, 1904 23 Axioms relative to type species 24 Rules and recommendations concerning types 24 A. Genera for which types are designated or implied in the original publication ...- •. 25 1. Genera originally published with only one species. " Mono- typical genera" 25 List of genera (chiefly nematodes) originally published with a single species 25 2. Genera originally published with only one valid species, but also with one or more species inquirendre 29 Nematode genera of this class 29 3. Genera originally published with a. species definitely desig- nated as type (type by original designation) 30 Roundworm genera with types by original designation... 31 4. Type by original implication through use of the specific name typicus or typus 31 Nematode genera wTith type determined by use of specific name typicus ~ 32 5. Type by absolute tautonymy 32 Cases of type by absolute tautonymy 34 Case of Angiostoma Dujardin, 1845 34 Case of Anguillula Mueller, 1786 34 Case of Capsulana Zeder, 1800 37 Case of Chaos Linnaeus, 1767 38 6. Type by virtual tautonymy 39 7. Types of rename! genera 40 8. Type by inclusion 42 9. Genera containing types of several earlier genera 47 Case of Acuaria, Spiroptera, Anthuris, and Dispharagus.. 48 5 6 TABLE OF CONTENTS. PART I. Principles involved in designating the types of genera of parasites— Page- Continued. Rules and recommendations concerning types—Continued. B. Genera for which types have been selected in later publications.. 52 10. Type by subsequent designation 52 Round worm genera with types by later designation 53 C. Genera for which no type has been definitely selected 55 11. Collective biological groups requiring no type species 55 12. Type by elimination .. 56 Elimination of species inquirendae (see p. 29) 57 Elimination of doubtfully referred species 57 Elimination of species selected as types of other genera.. 58 Restricted and unrestricted elimination 58 13. Preference to be shown to species not subsequently classified in other genera 60 14. Type by page precedence 62 15. Sexually mature forms take precedence over larval or imma- ture forms * 63 16. Preference to be shown to species examined by author of the genus 63 17. Preference to be shown to species named communis, vulgaris, officinalis, or medicinalis 64 18. The best described, best figured, best known, or most easily obtainable species 64 19. The original generic name to go with the greater number of species ^ 65 20. Special points to be considered in connection with genera of parasitic groups 65 21. Remaining genera mentioned in this paper 66 Correlated nomenclatural questions 67 22. Synonymy by original publication 68 23. Rule of homonyms 69 Round worm generic names which are absolutely preoccu- pied , 70 Roundworm generic names which absolutely preoccupy other names 71 24. Phononyms 72 25. Doubtful homonyms . 73 26. Emendation of names 76 27. Nomenclatural status of misprints 78 28. Origin of the Law of Priority 78 29. Rudolphi's Rules of Nomenclature 78 30. Polynomial authors between 1758 and 1819 80 Part II. List of generic names, chiefly nematodes, with their original and type species 81-150 Addenda 150 THE DETERMINATION OF GENERIC TYPES, LIST OF ROUNDWORM GENERA, WITH THEIR ORIGINAL AND TYPE SPECIES. BY CH. WAKDELL STILES, PH. D., Zoologist of U. S. Public Health and Marine-Hospital Service; Consulting Zoologist of Bureau of Animal Industry, AND ALBERT HASSALL, M. R. C. V. S., Assistant in Zoology, Bureau of Animal Industry. SUMMARY. Part I contains a general discussion on determination of generic types. A genus without a type species is like a ship without anchor or rudder, and a failure on the part of authors to designate types has been one of the most fruitful sources of trouble in systematic zoology and nomenclature. The existing codes of nomenclature recognize the importance of type species, but the rules for their deter- mination are not explicit enough, while the views on the method of determination vary greatly among authors. It seems desirable, but at present impracticable, to have complete, objective rules covering type determination, whereby the subjective element may be entirely elimi- nated, and whereby all types may be determined purely from the literature, without reference to the diagnosis or anatomy of an animal. Page precedence, as supported by many systematists, would accomplish this, yet would lead to many difficulties; still it must be admitted that this rule has great advantages despite its disadvantages. Although it seems impracticable at present to attempt to adopt any complete series of rules on type determination which shall be followed seriatim, still satisfactory rules can be formulated which will cover the majority of cases that arise, and these rules may be supplemented by recommendations which bring to mind methods which it will be well to follow, unless strongly contraindicated by practical consider- ations. While urging zoologists to designate the type of every new genus proposed in the future, we shall suggest to the International Commission on Zoological Nomen- clature the following rules and recommendations, as amendments to the Code, for guidance in determining the types in the case of older genera. 1. RULE.—A genus proposed with a single original species takes that species as type. (Monotypical genera.) 2. RULE.—The type of a genus (containing, from the standpoint of the original author, both valid and doubtful species) must never be selected from the species which the original author of the genus clearly designated as species inquirendftt at the time of the publication of the generic name. 7 8 BUREAU OF ANIMAL INDUSTRY. 3. RULE.—When in the original publication of a genus one of the species is definitely designated as type, this species should be accepted as type, regardless of any other considerations. (Type by original designation.) 4a. RULE.—If, in the original publication of a genus, typicus or typus is used as a new specific name for one of the species, such use shall be construed as "type by original designation." 4b. RECOMMENDATION.—It is well to avoid the introduction of the names typicus or typus as new names for species or subspecies, since such names are always liable to result in confusion later. 5. RULE.—If a genus, without designated type, contains among its original species one possessing the generic name as its specific or subspecific name, either as valid name or synonym, that species or subspecies becomes ipso facto type of the genus. (Type by absolute tautonymy.) 6. RECOMMENDATION.—If a genus, without designated type, contains among its original species one possessing as specific or subspecific name, either as valid name or as synonym, a name which is virtually the same as the generic name, or of the same origin or same meaning, preference should be shown to that species in desig- nating the type, unless such preference is strongly contraindicated by other factors. (Type by virtual tautonymy.) 7. RULE.—In case a generic name without designated type is proposed as a sub- stitute for another generic name, with or without type, the type of either when established becomes ipso facto type of the other. 8. RULE.—If an author proposes a genus, without designating a type, and includes among the original species [i. e., the valid species from his standpoint] the deter- mined type of an earlier genus, such type becomes ipso facto the type of the new genus.