CLASSIFICATION 15 



There are eight plates or valves in all on the back of 

 the animal, fitting one over the other like the tiles 

 on a roof. Generally the lorica is surrounded by a 

 leathery "girdle," so called, which helps to unite the 

 several plates, and which, though sometimes naked, 

 is usually studded with scales or beset with bristly 

 spines. 



In some forms the body is very long, and the 

 shelly plates are placed at intervals. The muscular 

 foot extends the whole length of the under surface 

 of the body; the end of the snout is just visible; 

 there are no tentacles. A row of small gills is seen 

 along each side under the edge of the mantle. The 

 valves are perforated for the passage of sense organs, 

 which in the family Chitonidse are in part converted 

 into eyes. When detached from the rocks to which 

 they cling, the animals will coil up after the fashion 

 of the well-known Wood-Louse. 



Order II. : The Aplacophora, or Solenogastra, 

 are so modified that they scarcely resemble molluscs 

 at all. The body is worm-like, and there is no trace 

 of a shell, but the much thickened outer skin con- 

 tains shelly spicules. The foot is extremely reduced, 

 or altogether wanting. The gills are in a chamber 

 at the latter end of the body, into which chamber 

 also the excretory orifices open. Their blood is red. 

 Two sub-orders are distinguished : 



Sub-Order 1 : Neomeniina (Plate IX., Figs. 4 

 and 5), in which the foot is sunk in a groove along the 



