722 CLASS XII. 
Crania Retzius, Bruce. Shell inequivalve, suborbicular. 
Affixed valve plane, with four muscular impressions internally, 
the two middle almost confluent to form one. 
Sp. Crania ringens HanineH., Anomia turbinata Pout, Test. utr, Sicil. 11. 
Tab. 30, Buainv. Malac. Pl. 59, fig. 2; Mediterranean. This species is 
commonly confounded with Anomia craniolaris L., which is fossil, like 
many other species, from the chalk-formation. 
Compare A. J. Rerzius Crania oder Todtenkopfs-Muschel, Schriften des 
Berliner Gesellsch. naturforschender Freunde, Bd. 11. 8.66, SowERBY Trans. 
Linn, Soc. X11. pp. 469—472, Tab. 26. 
II. Shell furnished with hinge. 
Calceola Lam. Fossil genus [of the Devonian period, Davipson 
Introduct. &e. p. 121]. 
Thecidea DEFR. 
Terebratula Luwyp, Brua. (species of Anomia L.). Shell 
inequivalve, subtrigonal. Apex of larger (ventral) valve perforated 
by a round aperture transmitting a short affixed peduncle. Hinge 
with two teeth. Internally two calcareous branches, slender, 
arcuate, rising from the dise of the lesser (dorsal) valve, forming 
the support of the arms. 
[The Z'erebratulide have been subdivided, inthe interest of Geology, 
into genera and sub-genera, chiefly according to the extent and form 
of the calcareous appendage. In the true Zerebratule the appendage, 
variable in length, is formed of two riband-shaped lamelle fixed to 
the crural base alone, and more or less folded back upon itself. 
Terebratulina D’Orxic. The crural processes united to form 
a calcareous band behind the mouth, and the reflected loop always 
in front of the mouth. | 
Sp. Zerebratula (Terebratulina) caput serpentis Lam., Anomia caput serpentis 
L., Encycl. méth., Vers. Pl. 246, fig. 7, Buatnv. Malacol. Pl. 52, fig. 6; in 
the Atlantic ocean, the North Sea, the Scottish coast. 
[Zerebratella D’Orzic. Differs from Zerebratula by its loop being 
doubly attached ; the lamelle proceeding from the crural base, before 
attaining their greatest length, sending off a flat horizontal process 
likewise affixed to a more or less elevated longitudinal septum. | 
Sp. Zerebratula (Terebratella) dorsata Lam., Buatnv. Malacol. Pl. 51, fig. 1, 
from the straits of Magellan, &e. 
[Megerlia Kine, Krausia Davipson, Morrisia Dav., Magas 
Sowerzy, Bouchardia Day., Agriope DrLtonescuames, Megathyris 
