1044 NEW YORK STATE MUSEUM 



another weaker one outside of this on each side. There are faint 

 indications of a third one beyond that. The shell is character- 

 ized by fine regular concentric lines which mark the edges of 

 narrow imbricating lamellae. Fine radiating lines, interrupted 

 by the concentric lines, are visible on well preserved specimens, 

 giving a surface sculpture essentially like that of S. coral- 

 line n s i s, S. v a n u x e m i and S. c r i s p u s . The fold of 

 the brachial valve occasionally shows a faint longitudinal 

 depression. 



Measurement of specimens from Becraft mountain. 



Width 



Length 



in mm 



in mm 



14 



11 



13 



11 



14.5 



11 



10 



8.5 



Pedicle valve 



Pedicle valve of type specimen 



Compared with the type from Williamsville, the present speci- 

 mens, though generally larger, are very similar. The outline 

 and median angular depression are alike in both. Only the 

 lateral plications of the pedicle valve are more rounded and 

 less widely separated in the Williamsville specimens than in 

 the Becraft specimens. The number is also less, so that, 

 whereas in the Williamsville specimens there is a total of eight 

 plications, only six can readily be made out in the Becraft speci- 

 mens. The concentric surface striae are the same in both. The 

 brachial valve of the Becraft specimens is somewhat more con- 

 vex, with the plications a little more pronounced, particularly 

 the ones next to the median fold. 



A single specimen from the Cobleskill of Schoharie (Am. Mus. 

 1S56, with Atrypa lamellata) approaches closely to 

 S. e r i e n s i s . The sinus widens regularly forward and the 

 sides are flat; the bottom, however, is still rounded. 



Genetic relationship of the Spirifers of the S. crispns type 



The similarity between S. corallinensis of the New 

 York Manlius and Cobleskill and S. modestus of the 

 Manlius 1 of Cumberland Md. has already been referred to. It 



