12 
APPENDIX. 
UNIVALVES. 
DIPLOCONCIIA. Conrad. 
Shell composed of two adhering tubes, one resting in a furrow on the 
side of the opposite tube. 
D. cretacea , pi. 2, fig. 26. Shell having sinuous tubes, minutely stri- 
ated across, and with acute distant ridges ; tubes separating towards the 
apex. 
This singular shell is not uncommon, but owing to its fragility has not 
been seen entire. 
Of several specimens of this shell none was found attached to shells or 
other substances, and no wood was seen accompanying them, but that 
might readily have disappeared, and the shell be allied to Teredo. 
CALLONEMA. Conrad. 
Conoidal, with spiral prominent lines, sutural space channelled, columella 
direct, thin, reflexed, projecting over the subbase and rounded at base, 
labrum thin. 
C. tuba ? bella , Conrad, is a representative of this genus which is pro- 
bably allied to Littorina, but the above generic diagnosis will distinguish 
the two genera from each other. 
Turrltella ventricosa Forbes is probably a species of this genus. 
C. Carolinensis , pi. 2, fig. 27. Shell with a prominent conoidal spire ; 
suture of last volution margined by a carinated line which disappears on 
the back of the shell ; spiral lines equal, prominent, Id on last volution, 
5 on penultimate volution, 3 first volutions entire. 
Smaller and proportionally shorter than C. bella. Being the only 
perfect specimen of the genus known to me, it is regarded as the type. 
ANCHURA. Conrad. 
A. rostrata, Morton, pi. 2, fig. 28. Shell with a broad, expanded 
labrum, acute at the apex and sinuous inferiorly ; beak straight, rather 
short, acuminate, labrum ridged on the back ; ribs longitudinal, acute, 
curved. 
Rostellaria rostrata , (Morton.) Gabb. Journ. Acad. Nat. Sci., second 
series, vol. 4, p. 390, pi. 68, fig. 7. 
