m> WORMS. 



25. NAIS. Body creeping, long, linear, depressed, pellu 

 cid : feet with small bristles each side : feelers none : 

 eyes 2 or none. 



26 . LERNAEA. Body oblong, roundish, naked, with 2 or 

 3 round tentacula or arms each side by which H 

 attaches itself: ovaries 2, projecting like tails from 

 the lower extremity. 



27. SEPIA. Body fleshy, receiving the breast in a sheath, 

 with a tubular aperture at its base : amis 8, beset 

 with numerous warts or suckers, and in most species 

 2 peduncled feelers : head short : eyes large : mouth 

 resembling a parrot's beak. 



28. TRITON. Body oblong: mouth with an involute spiral 

 proboscis: arms 6 each side, divided nearly to the 

 base, the hind-ones cheliferous. 



29. MEDUSA. Body gelatinous smooth, orbicular, gene- 

 rally flat or concave underneath : mouth underneath, 

 central. 



SO. ASTERIAS. Body depressed, covered with a coriaceous 

 muricate crust, grooved underneath, furnished with 

 feelers : mouth underneath, central, 5-valved. 



31. ECHINUS. Body more or less orbicular, covered with 

 a bony sutured crust, and generally clothed with 

 moveable spines : mouth underneath, 5-valved. 



ORDER III. TESTACEA. SHELLS. 



The calcarious covering of Molusca. 

 A. With more than two valves. 



32. CHITON. Inhabitant of the sbell a Doris: shell con- 

 sisting of several plates or valves disposed transversely 

 down the back, and incumbent on each other at their 

 anterior edge. 



33. BALANUS. Inhabitant a Triton : shell affixed by the 

 base, of many erect unequal valves. 



34. LEPAS. Inhabitant a Triton: shell affixed by a fleshy 

 peduncle, of several unequal valves connected by a 

 cartilage. 



35. PHOLAS. Inhabitant an Ascidia : shell with 2 large 

 valves open at each end, and smaller accessory-ones 

 at or near the hinge. 



B. With 2 valves. 



36. MYA. Inhabitant an Ascidia : shell generally gaping 

 an one end : hinge mostly with a strong thick broad 

 tooth not inserted into a groove in the opposite valve. 



37. SOLEN. Inhabitant an Ascidia : shell oblong, open at 

 both ends : hinge with a reflected subulate tooth, often 

 double, not inserted into a groove in the opposite 

 valre. 



