194 MANUAL OF THE MOLLUSCA. 
Shell, like a curyed gomphoceras ; siphuncle external. 
Distribution, 3 species. Silurian, New York. 
PHRAGMOCERAS, Broderip. 
Etymology, phragmos, a partition, and ceras, a horn. 
Type, P. ventricosum (Steininger species), Pl. II., Fig. 15. 
Shell curved, laterally compressed; apertwre contracted in the 
middle; siphuncle, ventral, radiated. Example, P. callistoma, 
Bar., Fig. 48. 
Distribution, 15 species. Lower Silurian—Carb.; Brit, 
Germany. 
CYRTOCERAS, Goldf., 1832. 
Etymology, curtos, curved, ceras, horn. . 
Synonyms, Campulites, Desh., 1832 (including gyroceras). 
Aploceras, D’Orbigny. Campyloceras and trigonoceras, McCoy. 
Gyroceras, D’Orbigny. 
Example, C. hybridum, Volborthi, and Beaumonti (Barrande). 
Shell curved ; siphuncle small, internal, or sub-central. 
Fossil, 84 species. Lower Silurian—Carb. ; North and South 
America and Europe. 
Fig. 59.* 
GYROCERAS, Meyer, 1829. 
Etymology, gyros, a circle, and ceras. 
Synonym, Nautiloceras, D’Orbigny. 
% Example, G. eifeliense, D’Arch. (PI. II., Fig. 18). Deyorian; 
ifel. 
* Fig. 59. Gyroceras Goldfussii. (= ornatum Goldf.). 5, siphuncle cf G. depressum, 
Goldf. sp. Devonian. Eifel From MM, D’Arching and Verneuil. 
a le eT 
