306 DESCRIPTION OF [Poly gas trica. 



506. ASPIDISCA denticulata. The denticulated Aspi- 

 disca. Lorica nearly circular, ends rounded, left side 

 truncated and denticulated ; the back is arched, the abdo- 

 men flat, and its hooked bristles are only visible when 

 climbing. Plate vii., Jig. 321, is an under view; and 

 figures 322 and 323 side views. Size l-576th. 



