CONCHOLOGY. 
a cavity in the middle, and a transverse deeply 
cloven lateral tooth each side, the segments of 
which divaricate from the beak. 
Includes Solen squamosus. 
54. Kellia, Shellsomewhat globular, equivalve, 
closed. Hinge with two approximate teeth and 
a remote lateral tooth in one valve, anda concave 
tooth and remote lateral one in the other. 
Includes Mya suborbicularis, and Tellina rubra. 
55. Nucula. Shell oval-triangular or oblong, 
equivalve, inequilateral. Hinge with an oblique 
projecting spoon-shaped tooth in each valve : lateral 
teeth on each side numerous, sharp pointed, 
inclining outwards, alternately closing together. 
Includes Arca Nucleus and A. minuta. 
CLASS IV. MOLLUSCA. 
Body without articulations or transverse seg- 
ments, furnished with head and eyes, and never 
inclosed in a bivalve shell, 
1, CHITONIDA. 
Body elongated, covered with numerous valves 
placed in a longitudinal series down the back. 
Includes the several species of Chiton,. 
2. PATELLIDA. 
Body conic, clothed with a conic shell which is 
hollow underneath. 
