130 CREPIDULA. 



section of the order Conchifera Dimyaria, Lam. In ttis section 

 the foot of the animal is thick, and the shell gapes considerably. 

 It is divided into the families Tubicolse, Pholadidse, Solenidae, 

 and Myaria. Fig. 44 to 76. 



CEASSISPIEA. Swainson. A sub-genus of CoiiUMBELLA, Auct. 

 for which Mr. Swainson quotes " Pleurotoma Bottse, Auct." 

 Crassispira fasciata, Sw. Lardn. Cyclop. Malac. p. 313. 



CEENATED. {Crena, a notch.) Applied to small notches, not 

 sufficiently raised or defined, to be compared to teeth. Ex. The 

 hinge of Iridina, fig. 150. 



CEENATULA. Lamarck, 1819. Fam. Malleacea, Lam. Mar- 

 garitacea, Bl. — Descr. Compressed, foliated, irregular, sub- 

 eqaivalve, inequilateral, oblique ; umbones terminal ; hinge 

 linear, nearly straight, with a series of excavations, containing 

 the cartilage, while the intervening ridges are covered with the 

 ligament, properly so called. Muscular impression oblong, in- 

 distinct. Obs. This genus is known from Perna by the hinge, 

 which in the latter is composed of a series of regular, straight, 

 ligamentary grooves placed across it. In Crenatula also there 

 is no passage for the byssus, as in Perna. C, Mytiloides, pi. x. 

 fig. 168. 



CEENELLA. Brown. A genus composed of Modiola discors 

 and similar species, having an oblique division between the 

 anterior and posterior portions of the sheU, and a crenulated 

 hinge margin. 



CEENELLA. ? See Trigokoc^lius. PI. vii. fig. 136. 



CEENULATED. Finely crenated or notched. 



CEEPIDULA. Lamarck, 1801. Crtpta, Humph, is used 

 in Gray's Synopsis as being the prior name, although it only 

 appeared by name in a catalogue. (Crepidula, a little slipper.) 

 Fam. Calyptraeea, Lam and Bl. — Descr. Oval, irregular, patel- 

 liform : apex lateral, incurved, or sub- spiral ; external surface 

 convex, smooth, vdth a flattish septum reaching nearly half across 

 the cavity ; epidermis light brown. — Obs. The diiFerence between 

 this genus and Calyptrsea is that in the latter the septum is 



