212 



ASCOCERAS, (JLOSSOPERAS, ETC. 



(4enu,s SYCOCERAS, Pictet. 



Shell oval or bottle-shaped. straioJit ; septa siui[)le ; siphunele 

 marginal. 



Silurian. Devonian. 

 S. ORTiiooAiSTKR, Sandl). PI. 97. tig. 491. 



Genus ASCOCERAS, Barr. 



Shell flask-shaiMMl ; the terminal chamber not only tills the 

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

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

 vent edges of the four or five incomiilete septa ; a minute siphunele 

 on the dorsal side. 



Sixteen species. L. and U. Silurian. Europe; Ganada. 

 A. BoHEMicuM. Barr. PI. 97. fig. 492. 



Genus GLOSSOCERAS, Barr. 



Shell like Ascoceras. but the dorsal margin of the aperture 

 ligulately extended and incurved. 



Two species. Middle and U. Silurian. An/icosfi, Bohemia. 



(^enus APHRAGMITES, Barr. 



Shell like A!iCoce?'a!<. but the septa are deciduous. 

 Two species. U. Silurian. Bohemia. 



Genus PHRAGMOCERAS, Brod. 



Shell compressed on the sides, curved ; a|)erture contracted In 

 the middle; last chamber large; si])huncle venti-al. with radia- 

 tions ; sei»ta simple. 



Fifteen species. Silurian to Devonian. Europe. 

 Ph. ventricosum. Stein. Pl.*97, fig. 49::!. Silurian. England. 

 Pn. CALLISTOMA. Barr. PI. 9S. fig. 494. Aperture. 



Genus GYROCERAS, Meyer. 



Shell planoi'boid, with separated whorls ; se})ta simple, but 

 little curved ; siphunele subdorsal, with radiations ; last cham- 

 ber large ; mouth but little contracted. 



Seventeen species. Silurian to Triassic (H- Europe; N. 

 America. 

 G. GrOLDFUSSll. 1*1. 98, fig. 495. Devonian. Eifel. 



