154 CONCHODERMA HUNTERI. 



Valves, narrow : scuta, trilobed, with the lateral lobe 

 not wider than the lower one : terga, with the upper part 

 bent almost rectangularly along the margin of the orifice : 

 carina considerably arched : peduncle short, blending into 

 the capitulum. 



No filament attached to the pedicel of the second 

 cirrus. 



Var. — Carina absent; scuta, with the upper lobe 

 absent; terga, with the rectangular projection little de- 

 veloped. 



Attached to the skin of a snake, probably the Hydeus or Pelamis bicolor, 

 and therefore from the tropical Indian or Pacific Oceans. Mus. Coll. of 

 Surgeons.* 



Capitulum, with the membrane very thin ; summit ob- 

 tusely pointed. Valves linear and thin. 



Scuta, elongated, flat, with the upper projecting lobe 

 rather more acuminated than the lower, and equalling it 

 in length ; lateral lobe not wider than the lower, and 

 about as long as it, forming an angle of about 55° with 

 the upper one. 



Terga, of somewhat variable length, generally about 

 half as long as the carina, narrow, and of nearly equal 

 width throughout ; lower point sharp ; externally convex ; 

 internally solid, with a trace of a central depressed line; 

 the upper fourth part generally a little bowed out of the 

 plane of the lower part, and abruptly bent at rather above 

 a right angle along the occludent margin of the orifice. 

 These valves are situated at about half their own length 

 from the upper points of the scuta. 



Carina considerably arched, extending to the lower 

 points of the terga, or running up between them for even 

 half their length ; equally narrow throughout ; scarcely 

 broader than the terga ; both points rounded ; internally 

 concave ; the lower point does not extend as far down as 

 that of the lower lobe of the scuta. 



* I owe to the kindness of Professor Owen, an examination of these 

 specimens, and information regarding them. 



