ONCHIDIUM. 51 



part of the groove between the mantle and the 

 foot ; foot narrowed ; shell none. 

 On rocks near the sea covered with the tides. 



1. Onchidium. 



Animal oblong ; mantle completely covering the 

 back, convex, coriaceous, tuberculated ; eyes 

 two, at the end of cylindrical retractile pe- 

 duncles ; tentacles none, or in the form of 

 rounded oral lobes or a buccal veil; jaws none, 

 tongue denticulated ; orifiice of reproductive 

 organs widely separated ; pulmonary cavity be- 

 hind the heart, with the aperture jjosterior, 

 between mantle and foot. 



11. 1. Onchidium celticum.- — Oblong mantle thick, 

 coriaceous, rather shining, covered with short 

 thick rounded tubercles, surrounded with smaller 

 ones ; foot oblong. 



Onchidium celticum. Cuvie?^ (?) ; Couch; Forhes and Hanley^ 

 iv. 3. t. F F F. f. 6. 



Inhab. Cornwall^ on rock at West Comb in Sand- 

 level Bay {J. Couch). 



The edge of the mantle considerably exceeds the 

 foot; the under side of this edge minutely granulated; 

 foot pale yellowish. 



" Jaws none ; tongue broad, and furnished with 

 vipwards of seventy transverse rows of blunt slightly 

 curved teeth, each row containing 108 teeth, and 

 divided by a minute central tooth of a triangular 

 form bearing a single blunt spine. The reproductive 

 organs are in the same individual. The male organ is 



E 2 



