MYA. GAPER. 97 



ten or twelve, very short, wrought with tubercled spiral 

 ridges, between which are three or four series of crenate 

 striee ; the base spirally striate : aperture small, oval, end- 

 ing in a slight canal: length an inch and a half j breadth 

 half an inch. 



In large shells the tubercles extend into long conic 

 spines on the larger volution, and sometimes run together 

 into a sharp spiral screw-like ridge. 



Weymouth, and northern coasts : very rare. 



26. Murex ad versus. Reversed Roclt-shsll. 

 Turbo reticulatus. Donovcnt, pi. 159^ 

 Turbo punctatus. Walker, L 48. 



Shell reversed, tapering to a fine point, opake, light- 

 brown : spires ten or eleven, scarcely defined by the line 

 of separation, with three rows of tubercles on each, the 

 middle row of which is smaller than the rest : aperture 

 oval, ending in a straight canal ; the base with two or three 

 smooth spiral ridges : length nearly half an inch ; breadth 

 hardly the eighth. 



Western and Scotch coasts : very rare. 



27. Murex minutissimus. Linn. Trans, iii. p. 65. 

 Shell taper, transparent ; spires five, with remote ribs, 



and .spirally striate ; canal closed. 

 Pembrokeshire coast : minute. 



MYA. GAPER. 



Shell with two valves, generally open at one end : 

 hinge with mostly a single broad thick spoon- 

 shaped tooth, generally not inserted into the oppo- 

 site valve. 



A. The teeth not inserted into the opposite valve, 1 to 17- 



B. The teeth locking Into the opposite valve, 18 to 24. 



1. Myatruncata. Abrupt Gaper. 



Lister, pi. 428. f. 269 Pennant, pi. 44 Da Costa, 

 pi. 16. f. 1 Linn. Trans, vi. pi. 14. f. 1, 2 Donovan, 

 pi. 92 Dorset Cat. pi. 3. f. 1 Wood, pi. 17-f. 1, 2. 



Shell oblong-oval, strong, broad, abruptly cut off at the 

 K smaller 



