ZOOLOGY 



* Midiivalves : shells in several parts* 



1. Chiton, Coat of Mail-Shell, lahabitant of the shell, a 



Doris. 



Valves many, disposed in an imbricated manner, or with 

 the edges lying one over another. Plate 4, fig. 1. 



All the Chitons are natives of the Ocean, and are gene- 

 rally found adhering to rocks or stones, that are overflowed 

 by the tide. 



1. Lepas, AcoRN-SaiELL. Inhabitant a Tr2Yo?2, 



Shell of several iipriglit unequal valves, adhering to various 

 extraneous substances, either by their bases, or by flex- 

 ible peduncles. 



This genus has been separated into two families ; the first 

 containing the Balani or Barnacle Shells, having flat 

 bases, plate 4, fig. 2, the second the Lepas, or Acorn-Siiells 

 affixed on flexible^ edimcles, Plate 4, fig. 3. 



The whole of this family are found adhering to various 

 substances within the influx of the sea, as the bottoms of 

 vessels, pieces of wood, or affixed to other shells. 



3. Pkolas, Pierce-Stone. Inhabitant an Ascidea. 



SAe// composed of two large valves and several lesser ones at 

 the hinge ^ which is recurved and toothed. Plate 4, fig. 4* 



The Phoitidcs inhabit clay, soft spongy stones, and wood, 

 situated beneath the surlttce t'f the water, which they per- 



