184 



more robust, the aperture more dilated, and the striae mueli more 

 crowded. Lamarck and others say that they may be distinguished 

 by the rectilinear beak of the antiqims. This also is a good char- 

 acter, but in my cabinet is a large and fine specimen of the latter, 

 of which the beak is as much recurved as in the present species. 

 PI. 29 ; upper and lower figures. 



Fusus ciNEREUS. — Specific character. With elevated costae ; 

 and transverse, filiform lines. 



Fusus cinereus, nob. Journ. Acad. Nat. Sci., vol. 2, p. 236. 



Obs. — This species is common in the estuaries of the eastern 

 shores of Maryland and New Jersey. It has considerable resem- 

 blance to two figures in Lister's Hist. Conch, pi. 924, f. 16, b, and 

 pi. 939, f. 34, a. The first of which is considered an uncertain 

 figure, and the latter is said by Dillwyn to be the undatus, and is 

 interrogatively referred to by Lamarck. Our shell certainly ap- 

 proaches the genus Purpura in habit, but it cannot enter with 

 Lamarck's characters. PI. 29 ; two middle figures. 



Paludina. — Obs. This genus may be distinguished from 

 Melania by the construction of the operculum, which has no other 

 than concentric lines of growth, whilst that of Melania has the 

 lines of accretion spirally radiate. 



The name of the genus was adopted by Lamark from Bruguiere, 

 but Montfort applied to it the name of Viviparws, which is re- 

 tained by Blainville inhis plate, though in the text he adopts 

 that of Paludina. 



Paludina ponderosa. — Specific character. Shell thick; 

 labrum more prominent towards the base. 



Paludina ponderosa, nob. Journ. Acad. Nat. Sci. vol. 2, p. 

 173. 



Obs. — This shell is common in many parts of the Ohio as well 

 as its tributaries. In its full grown state it is very thick and pon. 

 derous, enlarging so much in its body whorl, as to appear very 

 different from the young shell. In the early stages of growth it 

 resembles P. decisa, nob., from which indeed the back view would 

 hardly distinguish it ; but a sufficiently distinctive character re- 

 sides in the lower part of the labium, which in the decisa is not 

 obviously produced, whereas, in the present species it is consider- 

 ably advanced, as in many species of Melania, to which genus it 

 is closely related. PI. 30, fig. 1 



