NOVITATES ZOOLOGICAE XXIV. 1917. 19 



to the hair on the frons which in sociella forms a thick tuft, whilst in pellionella 

 it consists of loose hair ; in fact sociella exactly answers the generic description, 

 and pellionella does not. 



The Latin word Tinea means a larval insect pest ; it is used by Virgil for 

 the worms of moths that live in bee-hives, by Horace for book-worms, and by 

 other authors for those of clothes-moths, etc. 



The type of a genus is the species from which the original author described 

 that genus, and no action by a subsequent author or by all the Zoological Con- 

 gresses in the world can alter that fact. The difficulty is to determine what 

 that species is when the type is not indicated. The author would naturally 

 put his type species down first on his list, but he might subsequently rearrange 

 his list so as to get a more natural order of the species. Unless, however, there 

 is any evidence of this, such as the first species not agreeing with the generic 

 description, that species must be presumed to be the type. 



Under Tortrix Linne states that the larvae twist leaves, uniting them by 

 threads and living and feeding between them. The first species on his list, 

 prasinana, therefore cannot be the type, and the second species, viridana, becomes 

 the type. 



The type of Sphinx is ligustri, because Linne in Faun. Succ. states that it is 

 commonly called " The Sphinx " from the attitude of the larva. Similarly the 

 type of Bomhyx is mori because he calls it " The Bombyx," and the silkworm 

 exclusively was known by that name to the Greeks and Romans. 



Three methods are in use for determining the type of a genus when the 

 type is not indicated. 



1 . The above, which is used in the revision of the Sphingidae by Rothschild 

 and Jordan, the Catalogue of Lepidoptera Phalaenae in the British Museum, by 

 most of the authors in Seitz' Macrolepidoptera, and by most American authors. 

 It is the only method by which finality can be reached, and is rapidly coming 

 into general use. 



2. That the first reviser of a genus fixes the type of that genus. No two 

 authors seem to agree exactly in their interpretation of this law, or as to what 

 constitutes a revision, and whether a type has been fixed or not. Its chief 

 advantage seems to be that each author can continue to use a generic name 

 in the sense to which he is accustomed. 



3. That all species on the original list of a genus which have been used as 

 the types of later genera shall be eliminated, and one of the remaining species 

 be fixed as the type of the genus. 



This led to so many anomalies, such as the least applicable species being 

 fixed as the type of the genus, and even a species that the author of the genus 

 had never seen, that it has fallen into disuse. 



KEY TO THE GENERA. 



A. Hindwing with veins 3, 4 absent. 



a. Forewing with vein 4 absent, 6, 7, 8 stalked . . Paroxyptera, p. 27 



b. Forewing with vein 4 present, 6 from the cell . MetacJirysia, p. 30 



B. Hindwing with vein 3 present, 4 absent. 



a. Forewing with veins 6, 7, 8, 9 stalked. 



a'. Hindwng with the cell open . . . Arenipses, p. 36 



bV Hindwing with the cell closed . . . Paraphomia, p. 37 



