have characterized in different works, we can only discover 
two instances wherein the same species have been men- 
tioned by both parties, under different names. Our A. 
conica, is probably Lamarck’s virens, and belongs to the 
genus Pachystoma, Guild. ‘The other instance is curious : 
in the Appendix to the Bligh Collection, we described a 
remarkable variety of A. fasciata, under the sub-specific 
name of Canaliculata. In the following month appeared 
the second part of Lamarck’s Systéme, wherein this variety 
appeared as a species, under the very same name. It would 
almost appear as if the two accounts had been written at 
the same moment. We have since had good reason to be 
confirmed in our suspicion as to this shell being a mere 
variety of fasciata, from a fine series of specimens sent 
us from Demerara. We take this opportunity, however, 
of expressing a belief that our A. leucostoma, is the young 
shell of rugosa. 
