21 



Family BELLEROPHONTID^. 



BELLEROFHON BLAIRI, n. Sp. 



Plate Fig. 7, dorsal view of a cast; Fig. 8, dorsal view 



showing the shell below the aperture. 



Shell medium size, involuted, subglobose. Volutions expanded 

 very moderately until the aperture is approached, when there is a 

 more marked expansion, and recurved lateral lips. Umbilicus 

 small, outer lip with only a moderate sinus in front and sides ex- 

 panded, recurved and narrowly rounded. Aperture transverse aid 

 subreniform. The volutions sre rounded toward the apex, but 

 subangular on the sides of the last whorl. A slender dorsal baud 

 appears on the last volution which is somewhat obscure on the 

 cast but well defined on the shell. The surface of the shell is 

 ornamented with numerous fine strire that arise from the dorsal 

 band and curve gently forward and then backward over the ob- 

 tusely subangular sides where they become obsolete. These trans- 

 verse strife are not visible on the cast. 



This species is of the type of Bellerophon bilobatus from 

 the Lower Silurian and there are several Silurian and Devon iau 

 species that bear a more or less striking resemblance to it. There 

 is no difficulty, however, in distinguishing the species on making 

 a comparison. There is no defined species from the Subcarbon- 

 iferous rocks with which any comparison is necessary. The gen- 

 eral form and surface ornamentation readily distinguishes it 

 among species from rocks of the same geological age. 



Found by R. A. Blair, in whose honor we have proposed the 

 specific name, in the Chonteau limestone, near Sedalia, Missouri, 

 and now in the collection of S. A. Miller. 



BELLEROPHON SEDALIENSIS, n. sp. 



Plate III, Fig. 9, dorsal view of a cast; Fig. 10, lateral view of 

 part of a specimen preserving the shell. 



Shell medium size, involute, subglobose. Volutions expanded 

 very moderately until the aperture is approached when there is a 

 marked lateral expansion. Umbilicus open. Outer lip with a 

 moderate sinus and expanded narrowly rounded sides. Aperture 

 transverse and subreniform. The volutions are rounded toward 

 the apex, but subangular on the last whorl. The cast shows a 



