DETERMINATION OF GENERIC TYPES, ETC. 19 



41. A genus from its foundation belongs to one of three classes: 



(1) MONOTYPICAL (i. e., described from a single species, no other being known, or 

 described from a single specified species with which are associated other species 

 considered to be identical in structure). 



(2) ISOTYPICAL (i. e., described from more than one species, all of which are 

 congeneric). 



(3) HETEROTYPICAL (i. e., described from more than one species, these differing 

 in structure). 



(In class one, the single species described, or the single species cited, is the type. 



In classes two and three, the sum of the species therein contained constitutes the 

 "type" of the original author, unless it was indicated that one or more of these 

 species were not considered to be typical. ) 



42. If the author of an isotypical or heterotypical genus subsequently removes one 

 of his original types to another genus, this species ceases to be a possible type for 

 the genus in which it was first placed. 



43. In ascertaining the type of a genus not monotypical absolute adherence must 

 be given to the law of priority. 



44. He who first restricts a genus under its own name limits the possible type to 

 one of the species included in his restriction, but if possibly avoidable a heterotyp- 

 ical genus must not be restricted to the detriment of an existing monotypical or iso- 

 typical genus. 



45. When a heterotypical genus by restriction or specification of type becomes 

 monotypical, the single species to which it is limited must thenceforth be accepted 

 as the type of the genus, provided that this species had not previously been consti- 

 tuted the type of another genus. 



46. Restriction is effected by omission, by elimination, or by specification. 



47. The name of a heterotypical genus dates from its publication, but it dates as a 

 genus from the time that it became isotypical or monotypical; e. g., 



TOETRIX, Jones 1850 (heterotypical for) 



(1) viridana, Jones. 



(2) atrana, Jones. 



HETEHOGNOMON, Smith 1855 (type) liridana, Jones. 

 PANDEMIS, Smith 1855 (type) atrana, Jones. 



(Jones first published a generic name for which viridana was a possible type, but 

 Smith first established Heterognomon as a genus based on the type viridana. The 

 law of priority forbids the subsequent restriction of Tortrix to the detriment of Het- 

 erognomon, and therefore by elimination atrana was constituted the type of Tortrix, 

 Jones, with which Pandemis, Smith, is synonymous. 



N. B. For brevity of illustration a fictitious example has bean employed. ) 



48. If a subsequent author subdivide a heterotypical genus, distributing its types 

 among differently named genera but retaining the original name as a subgeneric 

 heading in more than one genus to which he refers a type, the law of priority shall 

 be rigidly enforced, and his first limitation shall be taken as restricting the type; but 

 should he in addition make use of the heterotypical generic name in a generic sense, 

 it shall be held that it was his intention to limit the type to the species referred to 

 in this sense, and his previous subgeneric limitation shall be ignored. 



e. g., (1) Hiibner published the heterotypical genus Eudemis, Verz. bek. Schm. 

 382 ( 1826) . Stephens adopted this name in a subgeneric sense for the four genera 

 Ditula Stph., Pseudotomia Stph., Cnephasia Crt., and Sericoris Tr. He constituted 

 profundana, F. (=porphyrana, Hb., Stph.) the type of the first subgenus so named 

 under Ditula. The law of priority should prevent any other species from becom- 

 ing the type of Eudemis Hb. 



