176 Quarterly Journal of ConcJiology. 



names, contrary to the generally accepted rule that generic names 

 only are to be taken from the Greek, and inflicting upon naturalists 

 a number of such jaw-breaking words as " sclerotricha'" ^^apalolena" 

 etc, notwithstanding that it ought to have been known that one of 

 the great hindrances to the spread of zoology is the terror such 

 names inspire amongst those who are thinking of taking up the 

 subject. 



Before the doctrine of evolution was promulgated, the definition 

 of a species was easy, it was then said to consist of all the individ- 

 uals descended from an originally created pair, but now such a 

 definition can no longer stand, and a species can only be consider- 

 ed as "true" for a limited period of time. We therefore must 

 regard the difference between a species and a variety as one of de- 

 gree rather than of kind, and from that point of view, Dr. Kobelt's 

 definition appears to me to be about the best I have seen. He 

 regards as distinct species such forms as can be readily distinguish- 

 ed one from another, without the neccessity of comparative measure, 

 ments, and without the aid of some indication of the locality, and 

 it should also be added without intermediate gradations. This 

 must at the some time be acknowledged to be rather an empirical 

 test, than a statement of what actually constitutes a species in nature. 



In my opinion the true difference between a species and a var- 

 iety will be found to consist in the production of perfectly fertile 

 hybrids by the latter — I do not make this statement in a pre-Dar- 

 winian sense, I believe for instance that Equus cahallus and Equus 

 asinus are simply modifications of a primitive Equus, but I regard 

 that point of differentiation at which two forms are no longer cap- 

 able of mutual reproduction, or only of the production of infertile 

 hybrids, as securing the perpetuation of the two forms, and this 

 giving them the range of species. 



Varieties are well defined as "incipient species". Divergence is 

 beginning, and may if circumstances favour lead to the production 

 of a distinct species. 



An intermediate class might here be introduced for variations 

 dependent on some local peculiarity of soil etc., affecting all the 

 individuals within range of the circumstances, but ceasing when the 



