132 Quarterly Journal of Conchology. 



distinguishing character not possessed by each; but H. rufescens is 

 never hispid except in a young stage of growth, and it is then 

 strongly keeled ; moreover, it is double the ske in an adult state. 

 He also considers that Clausilia laminata "much resembles C. bi- 

 plicata." I really do not know in what, and I do not think any 

 r.onchologist has any difficulty in separating them. The specific 

 distinction is sometimes more apparent in the animal than in the 

 shell, especially in the marine fauna, and if Mr. Simpson will study 

 the malakological side of the question, he will find that often where 

 the shell is intimately allied, the difference in the mollusc is much 

 greater. 



Mr. Simpson then declares: — "It is thus next to impossible to 

 discover the principle upon which conchologists proceed in manu- 

 facturing their species." Of course not, for there is no pri?iciple in 

 manufacturing species, or varieties. It is the "right of every na- 

 turalist to follow the bent of his own discretion or inclination in 

 the extension or reduction of species, subject only to the opinion 

 of his scientific compeers." And Mr. Simpson may even make a 

 var. decollata of his Limncea stagnalis (which, by-the-by, is of com- 

 mon occurrence) if he pleases, but it will depend on the weight of 

 ..his authority and experience if "the opinion of his scientific com- 

 peers" follow him. 



Every work on conchology contains disputable species and 

 varieties which give rise to criticism, for no author is infallible; and 

 though Dr. Gwyn Jeffreys' work may contain some apparent contra- 

 dictions, it embodies a mass of solid information and results of 

 careful study as is not to be found, in my opinion, in any other 

 work of the kind — or, in fact, all other works put together. 



In conclusion, I would point out that Mr. Simpson himself un- 

 wittingly quotes, from Dr. Gwyn Jeffreys' work, what must, after 

 all, be the standard for the guidance not only of conchologists, but 

 of all other sciences, in the determination of species : — "Certain 

 definite forms called species, exist and constitute more or less 

 extensive groups of individuals which resemble each other, as well 

 as their parents and offspring, to the same extent as we observe in 

 those of our own kind. These groups, to deserve the name of 

 species, must be distinct from others ; because, if any of them are 



