1042 NEW YORK STATE MUSEUM 



smooth apical portion, are the least accelerated, while the 

 extreme of acceleration would show strong plications on the 

 beak, with a median depression on the fold, which in extreme 

 cases commences near the apex. In rare cases is there a faint 

 median fold in the sinus of the pedicle valve. Similar modifica- 

 tion through greater or less acceleration is found in the mid- 

 Siluric relative of this species, S. c r i s p u s , which seems 

 to be a parallel development. 



Spirifer corallinensis Grabau 

 Geol. Soc. Am. Bui. 1899. 11:352. 

 This name was proposed, as a varietal one, for the character- 

 istic Spirifer of the Coralline (Cobleskill) limestone of Scho- 

 harie. This was referred by Hall toS. crispus and figured on 

 plate 74, Paleontology of New Yorh, v.2. The type specimen 1 

 is transverse, wider than high, with rounded ends. The sinus 

 of the pedicle valve is very shallow, rounded and 

 narrow. Beak of pedicle valve incurved and area (g; 

 comparatively low. In this respect the species is 

 like S. crispus. In a weathered-out specimen Kg. 6 Spirifer 



* r cp rallinen- 



surface markings similar to S. c r i s p u s are shown. si», pedicle valve 

 This species approaches closest to the simpler types of the 

 New York S. crispus, that with fewest plications. A speci- 

 men from Lockport [Am. Mus. col.J- 7 r — ] shows the relatively 

 high and subrhomboidal outline, with a shallower sinus, which 

 is rounded and widens less rapidly than in the normal form of 

 S. crispus. There is one moderately strong and one very 

 faint rounded plication on each side of the sinus, and two similar 

 though fainter plications on each side of the fold. 



Dimensions of the type specimen, length 11.5 mm, hight 

 of pedicle valve 10 mm, of brachial valve 8 mm, transverse 

 diameter 7 mm. Another characteristic specimen from the 

 same bed (Coralline of Schoharie) is figured by Hall [fig. 8d]. 

 It is proportionally narrower than specimen fig. 9d-f, and has 

 a somewhat more pronounced almost subangular sinus. The 

 width of this specimen is 11 mm, hight of pedicle valve 10.5 mm. 



I 



\Op. cit. pi. 74, fig. 9 d-f. Am. Mus. col. no. ±^p-. 



