Qua? terly Journal of Conchology. 211 



are not absolutely separated, one from the other, but the end of 

 the tooth is rather deeply channeled. The variations occur in the 

 laterals, the centrals being more uniform. The side edge of the 

 laterals is sometimes recurved for a considerable length." 



From this description of the animal, we can readily perceive its 

 analogies with other genera of this family, and I may add, that I 

 have taken as many as seven or eight young shells, with from rather 

 less than one whorl to more than two, from the ovaries of a single 

 individual. 



The history of the descriptions being given, and the generic 

 alliances proven, it remains to consider the validity of the three 

 species written. Prof. Haldeman united all three species under 

 T. magnifica, Conrad. In his review of this genus, published in 

 the Smithsonian work to which allusion has already been made 

 Mr. Binney agrees with Prof Haldeman in uniting T. 7?iagni_fica 

 and T. angulata^ but says with reference to T. Coosaensis, "Mr. 

 Lea's type of this species bears but little refemblance to V. rnagid- 

 Jica, yet Prof. Haldeman unites the tv.o. I myself have seen no 

 connecting links between them, though I have examined numerous 

 young individuals of V. magnifica.^'' In this latter decision Mr. 

 Binney was entirely correct, and the only wonder is how any per- 

 son, having seen the shells, could have decided otherwise. But in 

 reference to uniting the T. magnifica and the T. angulata, there is 

 by no means an equal degree of certainty. It must be borne in 

 mind, that the geographical distribution of shells is an important 

 factor in determining their specific relations; and in no case is this 

 fact more fully demonstrated, than in the study ot the fresh-water 

 operculates of North America. The Tulotoma angidata has not 

 been found in that part of the Alabama river whi(„h furnishes the 

 typical specimens of T. fuagnifica; at least such has been the result 

 of all my endeavours, and collections containing many hundreds 

 of specimens, of all ages and sizes, have reached me from all parts 



