SOME NEW DEVONIC FOSSILS 257 



This species with which I was at first disposed to identify the 

 shells in hand is usually of small extended form with a very regu- 

 larly convex ventral valve and broadly rounded plications. Though 

 distinct in outline and contour it often represents the aspect in 

 external and internal surface of S. cymindis. 



S. d e c h e n i Kayser [see Kayser. Fauna d. aeltest. Devon- 

 Ablag. des Harzes. 1878. p. 165, pi. 22, fig. I, 2]. 



This is a very large species but its smaller expressions, of which 

 I have specimens from the Kellerswald, are like S. cymindis 

 in degree of plication, though here it is the second rather than 

 the first pair of lateral plications that dominate the rest. The 

 ventral valve is uniformly convex but the umbo is not strongly 

 arched. 



S. n e r e i Barrande [as identified by Walther]. 



Specimens from the upper Coblentzian of Marburg very like this 

 shell in general aspect are somewhat more numerously plicated 

 but a distinctive feature lies in the very long dental plates such as 

 are present in S. 1 a t e i n c i s u s . 



Lower Devonic. Presque Isle stream, Chapman Plantation, Me. 



Spirifer cymindis var. sparsa now 



Associated with S. cymindis and quite as abundant, is a shell 

 distinguished in gross by its sparser plication. Our material here 



Spirifer cymindis var. sparsa 



presents us chiefly with a series of internal casts in which there 

 are some differences of expression, noted in particular in the fol- 

 lowing enumeration : 



1 Size. The shells are of medium size, uniformly approaching 

 S. arduennensis and S. cymindis in dimensions. Dif- 

 ferences in size and age are expressed on the internal cast by a 

 clearer definition in the younger and thinner shelled examples. 



2 Outline and contour. The marginal outline is subtriangular, 

 the hinge being long and sometimes extended at the angles, the 



