234 SCHIZOOHITON. 



Head valve with numerous (8-10) slits. Girdle densely clothed 

 with minute, convex, crowded scales. 



Section LORICA s. str. Caudal fissure deep ; sinus v-shaped ; 

 girdle widest at the sides, slit behind. 



Section LORICELLA Pils. Caudal fissure reduced to a shallow 

 wave ; sinus bilobed ; girdle widest in front, not slit behind. 



AA. Eyes developed upon the lateral areas. Sinus wide and large. 

 Insertion-plate of the tail valve reduced to a smooth ledge or ridge,, 

 having no posterior sinus or wave. 



Genus XVIII. ENOPLOCHITON Gray. 



Valves polished or deeply eroded, dark brown outside and within, 

 having excessively minute eyes scattered over lateral areas and 

 head valve (when not eroded) ; interior very densely and minutely 

 and peculiarly grooved and punctured. Girdle fleshy, bearing 

 separated rude scales. 



Genus XIX. ONITHOCHITON Gray. 



Valves polished, colored outside, porcellanous and smooth within,, 

 having the eyes disposed in radial bands on each lateral area and 

 the head valve. Girdle leathery, microscopically velvety. 



Genus XX. LIOLOPHURA Pilsbry. 



Valves lusterless, granulated, having the minute eyes scattered 

 over the lateral areas, sides of the central areas and head valve. 

 Girdle densely covered with stout calcareous spines. 



Genus XVI. SCHIZOCHITON Gray, 1847. 



Schizochiton GRAY, P. Z. S. 1847, pp. 65, 68, 169. 



Valves exposed, elongated, beaked, bearing a single row of eyes 

 upon each diagonal rib of intermediate valves and each radiating 

 rib of the head valve, the ribs of the latter corresponding in position 

 to slits in the pectinated insertion-plate. Sinus narrow. Posterior 

 valve having a deep posterior fissure, and several slits on each side 

 of it. Girdle slit behind, bearing small calcareous spinelets. Type 

 Ch. incisus Sowb. 



This genus might as readily be referred to Toniciince as to Liolo- 

 phurinw, for the posterior insertion -plate is well developed. The 



