155 



Mont, in Lin. T. II. p. 186. t. 1*2. f. 5,6. More 

 depressed and opaque than the preceding. Devon. 



GENUS. HALIOTIS. 



Ear-shaped, usually depressed ; spire very short, some- 

 times depressed and euljlateral ; aperture extremely 

 dilated, ovate-oblong and, when perfect, entire ; 

 disc, with perforations disposed in a line running 

 parallel to the left margin. 



H. TUBERCULATA. Lin. 1256. List. t. 611. f. 2. 

 Knorr. 1. 1. 17. /. I. Mart. f. 148,9. D.p. 1009. 

 Pen. 4. p. 141. t. 88. /. \44.-Don. t. 5. Mont. 

 p. 473. Dor. Cat. p. 57. t. 22. /. 1,2. Da Cos. t. 

 2. /. 1,2. Ovate-oblong, depressed convex, spirally 

 striated, with irregular longitudinal more or less distinct 

 rather distant folds ; brownish outside, often variegated 

 with green, beautifully irridescent within ; apex with a 

 single spiral turn, slightly produced, umbilical cavity 

 very small; inner lip inflected. 3. Guernsey. 



TRIBE. PLICACEA. 



Shell with plaits on the pillar, and the aperture 

 narrow. 



GENUS. TORN ATELLA. 



^Convolute, oval-cylindrical (usually striated transversty 



