56 Prof. F. M'Coy on sums new Silurian Mollmca. 



tcrior ends almost equal, elliptically rounded, ventral margin 

 gently convex ; valves slightly and evenly convex, the posterior 

 slope very slightly compressed ; surface apparently smooth ; 

 clavicular ridge strong, reaching rather more than half-way 

 from the beak to the ventral margin. Width 3^ lines, length 

 5 lines. 

 This is distinguished from the C. plunulatus (Conrad) by its 



regular oval form, larger and more oblique clavicular ridge and 



less elongation, and from the Cucidlcea {CucuUella) antiqua (Sow.) 



by the flatness and oval outline of the valves. 



Plas Madoc, N. of Llanrwst; abundant in the schists, Dolydd 



Ceriog Waterfall, E. of the Berwyn Mountains. 

 {Col. University of Cambridge.) 



Tellinomya lingula-comes (M'Coy). 



Sp. Char. Obovate, slightly and evenly convex; beaks small, 

 compressed, not prominent, close to the anterior end, which is 

 broadly rounded ; dorsal and ventral margins slightly convex, 

 converging towards the narrow posterior end, which is trun- 

 cated more or less obliquely, about two- thirds the width of the 

 shell under the beaks, and has an almost imperceptible sinus 

 between its inferior angle and the ventral margin ; surface 

 with fine irregular imbricating plicae of growth. Vv'idth 6 lines, 

 length i inch 1 line. 



This is much allied to the T. nasuta (Hall) of his Trenton 

 group, but is smaller, shorter and more regularly ovate. It has 

 somewhat the form of Cardinia with the delicate shell and eden- 

 tulous hinge oi Anodon. 1 believe this is about the oldest known 

 Lamellibranch, occurring in considerable abundance among the 

 Linguhe in the slates near Tremadoc, and from being about the 

 same size and texture may be confounded easily with them when 

 crushed. 



Slates, Penmoifa. 



{Col. University of Cambridge.) 



Sanguinvlites anguliferus (M'Coy). 



Sp. Char. Oblong, length three times the width ; beaks small, 

 half the width from the anterior end, which is subquadrate, 

 rounded ; posterior end subtruncate, not oblique, scarcely 

 wider than the width of the shell from the beak to the ventral 

 margin ; dorsal and ventral margins straight, almost parallel ; 

 a strong diagonal ridge runs from the beak to the inferior pos- 

 terior angle, immediately in front of which is the deepest part 

 of each valve ; from the beak to the anterior end is marked by 

 eight or ten narrow rounded ridges running obliquely down- 



