89 



This shell is much like A. lurida in shape, but is smaller and 

 more delicate. It occurs very rarely at Bradford Abbas quarry. 



ASTABTE DEPRESSA. FIG. 15. 



Lycett t. ix., fig. 11. 

 Goldf. t. 134, fig. 14. 



" Shell compressed, tranverse, ovately orbicular ; uinbones 

 median, prominent, obtuse ; lunule elliptical, narrow ; cardinal 

 margin nearly straight, oblique ; concentric costae convex, 

 irregular, with fine interstitial concentric striae."* 



Proportions : Length, 7 lines ; breadth, 7 ; depth, 5. 

 This shell occurs somewhat rarely at Bradford Abbas quarry. 



GKOUP m. 



OPIS. 



The remaining three forms have recently been separated from 

 Astarte under the name of . Opts, but as the fine example of A. 

 trigonalis of Sowerby is a general fossil at Bradford and else- 

 where, they are retained under the head of Astarte, placing the 

 term Opis of Desfrance in parenthesis. 



The Opis trigonalis, fig. 16, is a fine handsome shell, having 

 very boldly crenulated inner margins. It is commonly met with 

 in the basement beds of the stone above the sands at Bradford, 

 East Hill Quarry, Anbury Quarry, and at Halfway-house. The 

 other two species are always smaller, and are far less abundant. 

 Indeed, the latter has been confounded with the trigonalis 

 appearing to be a young example of the latter, but it differs in 

 its very small lunule. f 



* Morris and Lycett, Mollupca from Great Oolite, page 85 

 t Note by Editor. 



