28 
(c) All other things being equal, page precedence should obtain in selecting a 
type. 
(d) Species based upon sexually mature specimens should take precedence over 
species based upon larval or immature forms. 
(e) All other things being equal, show preference to a species which the author of 
a genus actually studied at or before the time he proposed the genus. 
(/) Show preference to a species bearing the name communis, vulgaris, medidnalis, 
or officinalis. 
(g) Show preference to the best described, best figured, best known, most easily 
obtainable species, or of which a type specimen can be obtained. 
( h ) Show preference to a species which belongs to a group containing as large a 
number of the species as possible. 
(i) In parasitic genera, select if possible a species which occurs in man or in some 
food animal, or in some very common and widespread host. 
Applying these rules to some of the generic names used by physi- 
cians, we arrive at the following results: 
Genus TAENIA Linnaeus, 17B8. 
Type, Tsenia solium. For generic synonymy see subgenera Tsenia (p. 28) and Tsenia- 
rhynchus (p. 29). 
Subgenus i^ENIA Linnseus, 1/38. 
1758: Tsenici Linnaeus, 1758a, « 819-820; type by elimination T. solium; also designated 
type by several authors. 
1777: Tenia Scopoli, 1777, 383; for Tsenia, hence same type (not accessible, reference 
taken from Sherborn, 1902, 962). 
1782: Hydatigena Goeze, 1782a, 42, 192; type by absolute tautonymy Tsenia hydatigena 
Pallas, 1766, 413, confined by elimination and inclusion to Hydra hydatula 
Linnaeus, 1767, equals Cysticercus tenuicollis. 
1782: J legoceplialos Goeze, 1782a, 42; only hence type species Tsenia vesicular is fascio- 
lata, equals Cysticercus fasciolar is. 
1782: ? Pseudoechinorhynchus Goeze, 1782a, 41, 138-139; ? type Ps. sp. Goeze, 1782a, 
138-139, equals ? Cysticercus fasciolaris. 
1786: Finna Werner, 1786, 10; not used in Linnaean sense; refers to Cysticercus 
cellulosse. 
1787: Yesicaria Muller, 17S7, 49-53; includes Hydatigena, Megocephalos, Multiceps, 
1782, and other forms; type by inclusion Cysticercus tenuicollis. 
1788: Yesicaria Schrank, 1788a, 29-32; includes Hydatigena, Megocephalos, and Multi- 
ceps, 1782, renamed; type by inclusion and page precedence V. orbicularis, 
equals Cysticercus tenuicollis; also type by virtual tautonymy Hydatigena 
vesicularis, equals Cysticercus tenuicollis. 
1790: Hydatula Abildgaard, 1790a, 33; type by absolute tautonymy Hydra hydatula. 
1790: ? Hseruca Gmelin, 1790a, 3050; only hence type species Hseruca muris Gmelin, 
? equals Cysticercus fasciola ris. 
1797: Hydatis Blumenbach, 1797, 415; not accessible; apparently only hence type 
species IT. finna, see Sherborn, 1902, 369, and Virey, 1798. 
1800: Alyselminthus Zeder, 1800a, 221-302; Tsenia renamed, hence same type. 
1800: Cysticercus Zeder, 1800a. 303-307; Hydatigena renamed, hence same type. 
o The short bibliographic references used in this paper are taken from Stiles & Has- 
sali, Index-Catalogue of Medical and Veterinary Zoology. 
