212 \SrnCKKAS, <i LOSSOCKK AS. KTC. 



Genus SYCOCERAS, Pictet. 

 Shell oval or bottle-shaped, straight ; septa simple; siphnnclc 



marginal. 



Silurian. Devonian. 

 S. oirniiMJAS'mt. Sandb. IM. <.>7. fig. 4<ll. 



Gonna ASCOCERAS, Barr. 



Shell flask-shaped ; the terminal chamber not only fills the 

 front of the shell. but extends down the ventral side, nearly its 

 whole length, as a deep cavity. which is embraced by the decnr- 

 rent edges of 1 he four or five incomplete septa ; a minute siphnncle 

 on the dorsal side. 



Sixteen species. L. and V. Silurian. /','// /-o/,r; Cnmuln. 

 A. BOHEMICUM. Barr. IM. 117. fiii'. 4112. 



Genu* GLOSSOCERAS, Ban. 



Shell like ASVWOV/N. but the dorsal mai'uiii of the aperture 

 ligulately extended and incurved. 



Two species. Middle and I". Silurian. Au/i<-< t .*/i\ Jio 



APHRAGMITES, Uiirr. 

 Shell like Axwwran. bnt the septa are deciduous. 



Two species. I". Silurian. 



Genus PHRAGMOCERAS, U.o-1. 

 Sliell compressed on t he sides, curved : aperture contracted in 



the middle: last chamber lai'u'e: siphnncle vent ral. wit h radia- 

 tions : septa simple. 



Fifteen sj)eeies. Silurian to Devonian. Enr<>i><'. 

 1*11. \ KXTiiicosi M. Stein. IM. ( .7, li.ii'. V.l-'l. Silurian. Kutjltmd. 

 I'll. CALI.ISTOMA. Uarr. PI. !>S. fig. I'.U. Aperture. 



Genus GYRCCERAS, M,-y-r. 



Shell planorl>oid. with separated whorls; septa simple, but 

 little curved; siphnnele snbdorsal. wit h radiation-'; last cham- 

 ber large: month but little contracted. 



Seventeen species. Silurian to Triassic (''). Kurnfn-; \. 

 America. 

 <J. (lOLDKiissn. PI. '.*. lig. r.i."). Devonian, ilih-l. 



