210 Prof. A. E. Verrill on the MoUusca 



The fact that there is in the southern and shallower parts of 

 the Gulf of St. Lawrence an isolated colony of southern shells 

 may have misled Mr. Jeffreys in many cases, especially as he 

 evidently consulted the Canadian collections much more than 

 those of the United States, many of the largest of which he 

 did not see at all. In respect of erroneous identifications and 

 the reduction of certain species to varieties, there is also much 

 to be said ; but this article is already so long that it will be 

 necessary to refer only to some of the more obvious and im- 

 portant errors of this kind, leaving the rest to be discussed 

 more fully elsewhere. 



. Every naturalist should be willing to allow his fellow natu- 

 ralists full liberty of opinion with respect to the specific identity 

 or difference of closely allied forms ; and no one can claim to be 

 infallible in such matters. Some of the errors to be mentioned 

 do not, however, come under this head ; for the species united 

 have only remote affinities. Nevertheless the naturalist who 

 has collected and carefully studied animals in their native 

 haunts, under various circumstances, in many localities, and in 

 great numbers, has, other things being equal, a very great ad- 

 vantage in these matters ; and therefore I believe that Mr. 

 Jeffreys would in most cases agree with me had he collected 

 and studied as many American shells as I have during the 

 past fifteen years, or if he were as familiar with them as he is 

 with the British species. In most of the cases to which I refer, 

 my own conclusions are in harmony with those of Dr. Stimpson, 

 who devoted so many years to collecting and carefully studying 

 our shells, and who is well known for his accuracy in such 

 matters. And it would be strange indeed if all American 

 naturalists, as well as many eminent foreign ones, have always 

 been making such ridiculous blunders in regard to some of our 

 most famihar shells as Mr. Jeffreys would have us believe. 



Thus he states (p. 240) that " Gfemma genuna^^ (or Tottenia 

 gemma) is the young of Venus mercenm-ia ! But it has long 

 been known to European as well as American conchologists 

 that the animal of gemma is very different from that of mer- 

 cenaria^ and quite peculiar ; that the hinge is constructed on a 

 very different type is well known ; and Prof. G. H. Perkins 

 has shown (Proc. Bost. Soc. N. H. 1869, p. 148) that gemma 

 is viviparous^ producing about three dozen young with well- 

 formed shells at one time. Moreover the young shells of 

 mercenaria^ smaller than the adult gemma^ are sufficiently 

 abundant on our shores, and may be seen in many American 

 collections ; they are certainly very unlike the gemma in form, 

 sculpture, and hinge, as has been well known for more than 

 thirty years. 



