21S 



the specimens are silicified, and I have been able thus to compare both 

 the mterior and exterior with the originals, on -which the species was 

 founded. 



2. 0. HiPPOLYTB, ante, p. 81, occurs at Cow Head in Division P. 



Besides the above there are several small convex finely striated species 

 of the type of 0. ferveta and 0. cluguntula. The specimens are so badly 

 preserved that it would be useless to name them. They occur at Port 

 aux Choix, Table-Head, Point Rich, and Bonne Bay. 



Strophombna aurora. (N. sp.) 



Fig. 202. 



Fig. 202. — Strophomena avrora; a, venlval valve ; b, section ; c, portion of the 

 surface enlarged. 



Description. — Semi-elliptical, length varying from a httle more than 

 one-half the width, to four-fifths of tlie width, widest at the hinge line ; 

 contour usually an uniformly elliptical curve from the cardinal angles all 

 round. Ventral valve convex, narrowly and often acutely carinated on 

 the u.mbo, depressed and sub-concave towards the cardinal angles. Area 

 moderate, forming an obtuse angle of about 125° with the plane of the 

 lateral margin. Dorsal valve concave, -with a mesial sinus commencing at 

 the beak and growing wider and shallower towards the front margin ; area 

 apparently about half the size of that of the ventral valve, and forming a 

 right angle there-with. Surface with rather strong angular striae of differ- 

 ent sizes, the smaller coming in between tlte larger, both by intercalation 

 and sub-division, the whole crossed by fine concentric striae, more distinct 

 in specimens which have the radiating strite well separated than in those 

 which have them close together. Tlie striae are about the size of those of 

 S. alternata, but more angular. The concentric strii-e are just visible to 

 the naked eye when the surface is well preserved. On most specimens they 

 cannot be seen at all, as a very small amount of weathering or exfoliation 

 removes them. In some there are several strong angular folds radiating 

 from the beak to the front margin, with usually one of the larger striae run- 

 ning along the crest of the fold, and a number of the smaller in the 

 intervening concave space. 



The convexity of this species, as indeed it is in all others of the genus, 



