172 Journal New York Entomological Societv, [Voi. xv. 



nomenclatorial view, it is immaterial whether an author describes his 

 genus or not, or whether he describes it wrongly, so long as the type 

 species is ascertained. This once ascertained, the genus is fixed, 

 although the characters of the type species may even contradict those 

 given by the author. What he states can have no weight except as to 

 the mention of the type. It follows that any genus originally contain- 

 ing no species mentioned by name, or only undescribed ones, is 

 invalid and to be ignored, no matter how fully described. It is a 

 nomen nudum and that name can be subsef}uently employed in any 

 sense. It also follows that the question of misidentification does not 

 arise, the species mentioned by the author as his type, or the one de- 

 termined by rule to be his type, is thereby the type, even though (if 

 the type be an old species) he may obviously describe another. 



The idea of Professor Williston, quoted in our last editorial, who 

 says : "I consider a genus as something more than a specimen," is 

 seen to be distinctly archaic and impracticable, while the complaint of 

 Professor John B. Smith, recently published in Science that his generic 

 names have been used in another sense than he intended by Sir G. F. 

 Hampson is without justice and due to a failure on the part of Pro- 

 fessor Smith to logically view the necessary result of the type idea. 



The rule for selecting types of genera when these are not specified 

 by the author becomes of the first importance, and its full discussion 

 at the present time is abundantly justified. 



BOOK NOTICE. 



A Natural History of the British Lepidoptera, a text book for students 

 and collectors. By J. W. Tutt, F. E. S. Volume V. London : 

 Berlin; 1906. 



We have the pleasure to notice another of Mr. Tutt's remarkably 

 full and detailed volumes. This one contains two chapters of general 

 matter entitled respectively "Hybridisation in Lepidoptera" and 

 " Mongrelisation in Lepidoptera," followed by a minute account of 

 the British Pterophorids. Agdistis is included, two superfamilies (!) 

 being recognized, the Agdistides and Alucitides, The former contains 

 the family Agdistidae, the latter the families Platyptilidge and Aluci- 

 tidse, and these are again divided into subfamilies, tribes and genera. 

 We have previously expresssed our opinion that Mr. Tutt gives his 



