DEVONIAN FOSSILS. 237 



Strophomena nobilis (M'Coy). 



Sp. Char. Semicylindrical ; entering (?) valve very gibbous near 

 the beaks, strongly arched downwards into a subcylindrical 

 deflected front, the sides of which are slightly flattened to join 

 the obscurely defined ears, which project from the gibbous 

 beak, and are nearly rectangular ; front rounded : surface ra- 

 diated with narrow distinctly defined ridges, of about equal 

 thickness throughout ; about twenty originating from the beak, 

 between each pair of which, after about the length of 1 inch, a 

 new ridge equal to the primaries in size is developed, so that 

 nearly over the whole shell the subequal ridges are little more 

 or less than a line apart ; the intervening spaces slightly con- 

 cave, three times wider than the ridges, crossed by very deep, 

 strong, irregularly curved concentric wrinkles, not crossing the 

 ridges, scarcely four in a longitudinal space of three lines; 

 entire surface, ridges and furrows marked with very fine 

 slightly irregular longitudinal distant striae, nine in the space 

 of 1 line, strongly punctured when the outer layer of shell is 

 removed. Width at hinge-line 2 inches 4 lines, proportional 

 length about the same, depth (greatest at one-third from the 

 beak) T%%. 



This fine species is so completely unlike any other, that it is 

 unnecessary to point out the distinctions ; the nearest analogue 

 apparently being the comparatively little, flat, few-ribbed Orthis 

 undulata (M'Coy, Synopsis of the Silurian Fossils of Ireland, 

 t. 3. f. 22. of the Silurian Series), with which however it has no 

 specific affinity. 



Devonian limestone of Torquay. 



{Col. University of Cambridge.) 



Leptodomus constrictus (M^Coy). 



Sp. Char. Oblong, or subtrigonal from the projection of the very 

 prominent beaks ; valves very tumid towards the anterior side, 

 greatest depth at about one-third from the beak ; anterior end 

 subtruncate, projecting but slightly towards the ventral por- 

 tion beyond the line of the beaks ; anterior lunette very large, 

 ovate, deep, smooth ; a deep narrow sulcus extends from the 

 beak, slightly widening to the nearly straight ventral margin, 

 which it meets at about 50^, forming a small sinus ; posterior 

 side much compressed, posterior slope not defined, posterior 

 end obtusely subtruncate with a slight obliquity ; hinge-line 

 straight, rather shorter than the posterior sid©; anterior side 

 and middle of the valves deeply marked with coarse concentric 

 wrinkles, arising from the edge of the smooth anterior lunette, 

 and most of them becoming abruptly obsolete on the posterior 



