256 NEW YORK STATE MUSEUM 



fully determined. Distinctions are refined in this series of fossils 

 and the differentials of the shell before us can best be indicated 

 by comparisons with other members of this series. 



In a general way, however, it may be said that S. cymindis is 

 a shell of larger size and stouter proportions than S. subcuspi- 

 datus lateincisusof the Presque Isle outcrops. The form is 

 short-winged with a prominent and arched ventral beak, well devel- 

 oped subangular median sinus and fold, the width of the former 

 equaling the distance between three to four radial furrows ; of the 

 latter that of three plications. Both sinus and fold have, abruptly 

 sloping sides and a narrow bottom and top. The primary plica- 

 tions are conspicuous by their elevation beyond the rest. The 

 radial plications are rounded on the exterior with sharp and nar- 

 row furrows, sharper on the internal cast with broader furrows. 



Spirifer cymindis 



There are seven to eight plications on each lateral slope. In rare 

 instances there is a faint median plication in the sinus. Fine con- 

 centric growth lines with traces of fimbriae cover the surface. 



The dental lamellae are short divergent and inconspicuous, the 

 muscle scar of the ventral valve small, well defined, deeply divided 

 by the median sinus. The shell is not greatly thickened about this 

 area and the inner surface adjoining is rarely pustulose. 



Comparisons. S. concinnus Hall. In this Helderbergian 

 form we have a shell of like proportions but with much more ele- 

 vated ventral beak and broader cardinal area, more abundant plica- 

 tion, 10 to 12, greater width of fold and sinus and extended pro- 

 jection of the sinus on the anterior margin. 



I am here again indebted to Professor Kayser and Dr Drever- 

 mann for affording facilities and suggestion for comparison with 

 European species of the early Devonic. 



S. arduennensis Schnur [see Schnur. Brachiopoden der 

 Eifel; Palaeontographica. 1854. 3 :I 99> P 1 - 3 2 > fi g- 3 J Kayser, Fauna 

 des Hauptquartz. 1889. p. 33, pi. 2, fig. 1-4; pi. 9, fig. 3; pi. 12, 

 fig. 5; pi. 16, fig. 1-9]. 



