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Genus STREPTELASMA. Hall. 



[Ety. : Streptos, twisted: elasma, lamella.] 

 (Pal.. N. Y., Vol. L, p. IT.) 



Coralluin simple, turbinate and often curved. Septa- 

 numerous, those of the earlier cycles all reaching the center, 

 where they are twisted into a psewlo-columella; those of 

 the last cycles short. Dissepiments present. Epitheca well 



developed. 



STREPTELASMA RECTUM. Hall. ( Fig. 2. ) (111. Dev. 



Foss., PI. XIX.) 

 Distinguishing Characters.— Rather small size: conical 



outline; rapidly tapering- toward the base: twisting of the 



septa near the center of the calyx, 

 and formation of a solid axis or 

 psendo-columella ; slight development 

 of dissepiments: height. 3 or 4 cm.; 

 diameter of calyx, 1 .5 to 2 cm. 



Found in the lower Moscow shales 

 near the head of Section 5; also in 

 the Demissa bed at Section • >. and 

 in the Trilobite beds and the shales 



below them down to the Nautilus bed, at Section 8, 



on the Lake Shore, and in the bed of Avery's Creek. It is 



usually abundant. 



STREPTELASMA UNGULA. Hall. ( Fig. 3.) 



(111. Dev. Foss.. PI. XIX.) 



Distinguishing ('Itaractcrs.— Smaller size than 



S. recta; less degree of tapering; curved or 



horn-shaped outline;; slight twisting of septa 



at the center. 



Fig. 3. strept- Found in the lower Moscow shales, between 

 elasma ungula 

 CafterHaU). Sections 4 and .">. 



Fia. 2. Streptelasma rectum 

 (after Hall), (a) cardinal sep- 

 tum ; (6) alar septum. 



