14)6 SHELLS AND SHELL- FISH. PART I. 



It thus appears that each type of the Rostellaria;, as 

 arranged according to their affinities, turns out to be a 

 representation of one of the genera of the StrombintB : 

 and these analogies are so perfect, that it appears to us 

 absolutely impossible they could be more complete at 

 least, in regard to the shells ; although they would be 

 even more beautiful, when accompanied by a corre- 

 sponding relation in the animals. R. rectirostris is the 

 fourth type, and not the common curvirostris ; because 

 this latter is intermediate in structure between the 

 former and R. fissurella. 



(136.) We feel persuaded, that if the concluding 

 volumes of the elaborate work of Lamarck had not been 

 finished "under the eyes of another," because their 

 celebrated author had become blind, we never should 

 have seen our Rostellaria cancellata and canalis placed 

 in his genus Strombus. No species, in fact, either of 

 Strombus or of Pterocera, so far as we know, occur in 

 a fossil state. It appears hardly necessary, in so limited 

 a group, to impose sub-generic names of these types ; 

 for if one is named, all should be so. Such designations 

 are not necessary to facilitate research, when the whole 

 genus contains not more than, perhaps, a dozen species. 

 With the mitres, the cones, and the land snails, &c., the 

 case is very different : such groups contain hundreds of 

 species ; and by designating their sub-genera under 

 patronymic names, most material help is afforded, in all 

 ways, to minute research, or to general views. 



(137) The connection of the CONESUE, or cones, with 

 the Strombince, is effected by- our new genus Strombidea 

 in the latter, and Terebellum in the former. The affini- 

 ties of these two genera we pointed out many years ago, 

 by the publication of a shell which actually unites the 

 characters of both *; and Lamarck entertains no doubt 

 of the close connection of Terebellum to Conus. Tere- 

 bellum, in short, merely represents the olives in this 

 circle, without having any real affinity with them ; but 



* Strombus dubius. See Taylor's Phil. Mag. 61. No. 301. May, 1823. This 

 will now be our Slrombldea dubia. Specimens are in the rich collection 

 f Mr. Stanford. 



