CARYCHIUM. 465 



character by European writers ; but, of several specimens sent me 

 by Mr, Sowerby, only one bad them. In fact, it must be very doubt- 

 ful Avliether the species described under the names of bidcntata, trip- 

 licata, pusi/lus, alba, ring-ens, rejiexa, and perhaps Finnini, arc 

 anything more than modifications by age, accident, and locality, of 

 this same species. 



[I have placed this sliell in tliis genus on the authority of Pfeiffer 

 and of Adams's Genera. It has been placed in many different gen- 

 era by European authors. In America it has been considered an 

 Auricula by Gould and others, until Stimpson classed it among the 

 Melampi. From the exterior of the animal there appears no differ- 

 ence between it and Melampus bidentatus. It does not even agree 

 with the animal of Alexia, given by Adams in the " Genera of Re- 

 cent Mollusca," which I have copied on pi. 75, fig. 22, of " The Ter- 

 restrial Mollusks." Tliis figure represents the true Alexia denticu- 

 lata, Montfort, Avith which Gould confounds this species. The shell 

 is also quite distinct. It is, liowever, united to Alexia myosotis, by 

 Forbes and Hanley, in their work on " British Mollusca," and by 

 Moquin-Tandon. Pfeiffer considers them distinct, as does also 

 Reeve. 



It is probably an imported species, as Stimpson remarks (" Shells 

 of New England"), being found only in the Atlantic seaports. At 

 Boston it is common on old wooden wharves in the harbor. It is 

 also found on isolated stones wliicli are immersed by the rising tide 

 at least four hours out of tlie twelve. When placed in fresh water 

 it becomes benumbed and dies ; it will live without water in captiv- 

 ity several days. 



aeniis CARYCHIUill, Muller. 1774. 



Foot not transversely divided beneath. 



Sliell pupa-shaped, very thin, transparent, with but few whorls ; 

 aperture sub-oval, with one dentiform columellar fold, sometimes 

 obsolete ; parietal wall with one or two teeth ; peristome expanded, 

 terminations not approximating, the right hand one with one inter- 

 nal tooth. 



Jaw slightly arched, without ribs or marginal denticulations, 

 hardly striated towards the margin. 



Teeth in slightly bent cross series, central equilateral, narrow, 



laterals broad, short, denticulated. 

 30 



