NAUTIIilD^. 55 



AscocERAS, Barr., 184Y. 



Etym. — Ascos^ a leather bottle, ceras, a horn. 



Syn. — Cryptoceras, Barr., 1846. 



Distr. — 16 sp. L. and F. Silurian ; Europe, Canada. A. Bohe- 

 micum, Barr. (xxx, 3). 



Shell flask-shaped ; the terminal chamber not onlj^ fills the front 

 of the shell, but extends down the dorsal side, nearly its whole 

 length, as a deep cavity, which is embraced by the decurrent 

 edges of the four or five incomplete septa ; a minute siphuncle 

 on the ventral side. 



Glossoceras, Barr., 1865. 

 Etyra. — Glossa, a tongue, ceras, a horn. 

 Distr. — 2 sp. M. and U. Silurian ; Anticosti ; Bohemia. 

 Shell like Ascoceras, but the ventral margin of the aperture 

 ligulately extended and incurved. 



Aphragmites, Barr., 1865. 

 Etym. — A, without, ^/iragfrnos, a partition. 



Distr 2 sp. TJ. Silurian ; Bohemia. 



Shell like Ascoceras, but the septa are deciduous. 



Phragmoceras, Brod., 1839. 



Etym. — Phragmos, a partition, and ceras, a horn. 



Syn. — Campulites, Desh. (part), 1832; Phragmolites, Conr., 

 1838. 



Distr. — 50 sp. Silurian to Devonian; Europe, N.America. 

 Ph. ventricosum, Murch. (xxx, 4). Silurian; Engl^lnd. Ph. 

 callistoma, Barr. (xxxi, 6). Aperture. 



Shell compressed on the sides, curved ; aperture contracted 

 in the middle ; last chamber large ; siphuncle dorsal, with radia- 

 tions ; septa simple. 



Gyroceras, de Koninck, 1844. 



Syn. — Nautiloceras, d'Orb, 184t. Polycronites, Troost (?), 

 1840. 



Distr. — 40 sp. Silurian to Triassic (?) ; Europe, N. America. 

 G. Goldftissii, Arch, (xxxi, 7). Devonian; Eifel. 



Shell planorboid, with separated whorls; septa simple, but 

 little cu.rved ; siphuncle excentric, with radiations ; last chamber 

 large ; mouth but little contracted. 



Nothoceras, Barr., 1856. 



Distr. — N. Bohemicum, Barr. (xxx, 5 ; xxxi, 8). TJ. Sikirian ; 

 Bohemia. 



Shell nautiloid, slightly involute ; septa but little curved, not 

 lobed. 



