CLASS IX. ORDER IK. 



ASCIDA, body fixed, roundish and aparently is- 

 suing from a sheath. In sea. 



DAGYSA, body loose, nayant, angular, tubular 

 and open at each extremity. In sea. 



PTERQTKACHEA, body detached, gelatinous, 

 with a moveable fin at the abdomen or tail ; eyes 

 two, placed within the head.. In sea. 



DERRIS, body cylindric, composed of articula- 

 tions ; mouth terminal ; feelers two. In sea. 



ONCHIDIUM, body oblong, creeping, flat beneath ; 

 mouth placed before ; feelers two, situate above 

 the mouth ; armes two, at the sides of the head ; 

 vent behind, and placed beneath. On leaves. 



LOB ARIA, body above convex, beneath flat, la*- 

 bate. In sea. 



ORDER 2. MULTIVALVA. 



Soft animals, having shells with more than two 

 valves. 



CHITON, (monoloba,) animals inhabiting the 

 shell, adoris ; shell consisting of several segments 

 or transverse incumbent valves, disposed in a lon- 

 gitudinal series down the back. 



LEPAS, (acorn-shell, barnacle,) animal a tri- 

 tcn ; shell affixed at the base and consisting of 

 many unequal erect valves* Formerly called the 

 barnacle goose-egg, 



PHOLAS, (piddock,) animal an ascidia ; prin- 

 cipal shell bivalve divaricate, with several lesser 

 differently shaped accessary ones at the hinge j 

 hinges recurved, united by a cartilage ; in the itt^ 

 side beneath the hinge is an incurved tooth. 



