118 
MOLLUSCA. 
Orbicula, Cuv. 
The Orbiculte have two unequal valves, one of^ which, that is round 
and conical, when viewed by itself, resembles the shell of a Pa- 
tella; the other is flat and fixed to a rock. The arms of the animal, 
— Criopus, Poll, — are ciliated and spirally recurved like that of the 
Lingulae. 
The seas of Europe produce a small species. Patella anomala. 
Mull., Zool. Dan. V, 26; Anomia turbmata, Poli, XXX, 15 ; 
Bret. Sowei’b., Lin. Trans., XIII, pi. xxvi, f. 1. 
The DisciNjE, Lam., are Orbiculae, the inferior valve of which is 
marked by a fissure. The 
Crania, Bru(j. 
Should be approximated to the Orbiculae. The arms of the animal 
are also ciliated, but the shells have deep and round internal muscu- 
lar impressions, that have caused it to be compared to the figure of 
a skull. 
One of them inhabits European seas; Anomia craniolaris, L. ; 
or Crania personafa, Bret. Sowerb., Lin. Trans., XIII, pi. xxv, 
f. 3. Several are fossil ; such as the Cran. antiqua, and the 
others of which M. Hoeninghaus has given an excellent Mono- 
graph. 
CLASS VI. 
CIRRHOPODA 
[Lepas and Triton, Lm.] 
The Cirrhopoda, in several points of view, are intermediate between 
this division and that of the Articulata. Enveloped by a mantle, and 
testaceous pieces which frequently resemble those seen in several of 
the Acephala, their mouths are furnished with lateral jaws, and the 
abdomen with filaments named cirri, arranged in pairs, composed of 
a multitude of little ciliated articulations, and corresponding to a sort 
of feet or fins similar to those observed under the tail of several of the 
Crustacea. Their heart is situated in the dorsal region, and the 
branchiae on the sides ; the nervous system forms a series of ganglions 
* M. De Lamarck has changed this name into Cirripeda, making it a class. 
M. de Blainville also makes a' class of them, but he changes the name to Nemato- 
PODA, and places them wdth the Chitones, in what he calls his tjpe of the Malen- 
TOZARIA. 
