202 DR. P. P. CARPENTER ON NEW MOLLUSCA. [Feb. 14, 
obtain an adult shell, which passed into the Cumingian Collection. 
Having removed the animal matter with great care, the loop was 
found to retain the form seen in the young shell, only perhaps still 
more open. This is the first recent species of the genus which has 
been discovered with a sculptured surface, and affords an instructive 
lesson not to rely on external characters. 
Terebratula unguicula: 1, 2, outside views of Mr. Cuming’s adult specimen, 
natural size: 3, 4, inside views of the upper valve, slightly magnified. 
The outline of the adult is much rounder, and the margin blunter, 
than in 7’. caput-serpentis. Inside, the noncompletion of the some- 
what w-shaped loop is a very obvious character. This is large in 
proportion, extending to about two-fifths of the length and one- 
third of the greatest breadth of the shell. It is bent upwards in the 
middle, as seen from the partly opened valves ; with a double wave at 
the sides, as seen from the direction of the opposite valve. Two spurs 
ascend from the crests of the side waves, as though preparing to 
complete the loop. The similar Terebratella angustata from Japan, 
when of the same size as Dr. Cooper’s specimens, has the loop quite 
continuous *. 
Subgenus NETTASTOMELLAT. 
Pholadidea: valvis postice in calycem testaceum planatum pro- 
longatis ; calyce coriaceo nullo. 
NETTASTOMELLA DARWINII, Sby. (diag. auct.). 
N. ¢. minore, elongata, tenuissima; parte postica costis radian- 
tibus acutioribus circ. vil. e€ laminis concentricis acutissimis, 
distantibus, antice continuis, elegantissime ornata; rostris pla- 
* Dr. Cooper having forwarded for my inspection a large aud beautifully per- 
fect specimen_of the true Waldheimia californica, | have compared it with the 
series of the very variable W. globosa in the Smithsonian Museum, undoubtedly 
from Orange Harbour. In shape, and in the form of loop, I can detect no dif- 
ference. The Californian shell, however, has a strong brownish-red tinge, and 
does uot display the beautiful veining of the Maghellan species. 
+ Th. vqrra, a duck, oréya, mouth. The name Netastoma, given in the 
‘ Brit. Assoc. Report,’ 1863, being preoccupied in another subkingdom, according 
to Dr. Cooper, it is thought necessary to vary the termination. 
