370 Mr. R. I. Pocock on Hen- Verhoefs Subdivisions 



to it by its founder. For purposes of nomenclature generic 

 and subgeneric terms are equivalent. If a genus be split into 

 two or more subgenera, the subgenus which contains the type 

 species of the genus must receive the generic name, A generic 

 or subgeneric name must not be consigned to oblivion on the 

 grounds that the species referred to it prove to be capable of 

 liner division ; nor yet upon the grounds that the character 

 upon which it was based proves in itself to be not of generic, 

 or subgeneric, or even specific value. It can only be finally 

 sunk as a synonym when it has been shown that its type 

 species possesses no other character of generic or subgeneric 

 importance. And, lastly, when a generic name has once 

 been published by an author, neither he nor anyone else has 

 the power to replace it by another, unless preoccupied, nor 

 yet to transfer it from one set of species to another. 



Herr Verhoeff seems to me to have disregarded all these 

 rules ; nor has he been careful to avoid the use of names 

 already in vogue. An instance or two will illustrate my 

 meaning : — The type of /m^ms, Linn., must he, Q\t\\QY sahulosus 

 or terrestris ; but neither of these species is referred to lulus 

 by Verhoeff. The species named lulus fostidus by Koch 

 received the subgeneric name Unciger from Brandt ; but, for 

 no valid reasons, Verhoeff proposes Oncoiulus for the same 

 species. The genus Pachyiulus of Berlese is adopted, but it 

 is divided into two subgenera — Megaiulus and Acanthoiulus j 

 but Megaiulus is equivalent to Pachyiulus, and Acanthoiulus 

 was used over fifty years ago for perhaps the best-marked 

 genus in this same group of Diplopoda. Leptoiulus includes 

 fallax of Meinert, which is the type of Ophiulus of 

 Berlese ; and since it appears to be admitted that triline- 

 atus, Koch, the type of Leptoiulus, is congeneric with 

 fallax, it is clear that Lepioiulus is a synonym of Ophiulus. 

 Brachyiulus of Berlese and Anoploiulus, Verhoeff, are syno- 

 nyms, because they have the same type species, pusillus. 

 Leach ; and Leucoiulus is similarly synonymous with Alla- 

 iulus, &c., &c. To pursue further the inquiry as to the 

 stability of the other genera and subgenera proposed would be 

 beyond my present purpose ; but the following table will, I 

 think, show, at all events approximately, the genera and sub- 

 genera of European lulidge. 



I may add that, since Herr Verhoeff has not seen the 

 necessity to state which species out of a number is the type of 

 a genus or subgenus, I have here ventured to save him this 

 trouble by selecting the first. 



1. luLUS, Linn. {= Ommatoiulus, Latz. ; Archiulus, Berl. ; Mesoiulus, 

 Verb. 1893, not 1894 ; Bothromlus, Verb. 1894). 

 Type sabulosus, L. 



