134 New Genera and Species of Brachiopoda. 



The following figures exhibit the difference in form between 

 Stricklandia and Pentamerus : — 



Fig. 8. 



Fig. 9. 



Fig. 10. 



Fig. 8. Stricklandia lens, dorsal view. 

 " 9. do. do., side view. 



" 10. Pentamerus Knightii, side view. 



I am not certain whether Fig. 9 is the true S. lens or a variety. 

 It is more pointed in front than any of the English specimens 

 that I have seen. 



Stricklandia, Gasp£ensis, Billings. 



Description. — Shell, large, oval ; length to breadth about as 

 five is to four ; valves about equally convex. The ventral valve 

 has a shallow mesial depression which commencing at the beak 

 in a point gradually enlarges to the front margin, more than half 

 of which is affected by it ; the dorsal valve has a corresponding 

 mesial elevation, on each side of which there is sinus of just 

 sufficient strength to induce the idea of a trilobed surface. The 

 two valves are nearly equal, the ventral being the longest by 

 about one line in a specimen five inches in length. The beak of 

 the ventral valve is closely incurved over that of the dorsal and 

 on each side of it there is a short area. The whole surface 

 is covered with strong close rounded longitudinal ribs with rather 

 sharp furrows between. These ribs are on an average one line 

 wide at the front margin. 



This species, differs from all the others in its form, which is 

 a nearly perfect ellipse, both ends being about equally rounded 

 and the greatest width being in the centre of the length. The 

 ribs are also more distinctly defined and proportionally more 

 numerous than these of any other species. 



The average length is four inches ; width three inches and a 

 half ; depth of both valves two inches and a half. 



