350 MANUAL OF THE MOLLUSCA. 
Synonyms, Creseis, Forbes.* Pugiunculus, Barr. 
Shell straight, conical, tapering to a point, back flattened, 
aperture trigonal. Length, 1-8 inches. 
Fossil, 40 species. Paleeozoic. North America, Britain, New 
South Wales. ? Permian. 
PTEROTHECA, Salter. 
Type, P. transvyersa, Portlock. 8 species, Lower Silurian ; 
Ireland, Wales, Canada. 
Shell bi-lobed, transversely oval, witha dorsal keel projecting 
slightly at each end; ventral plate small triangular. 
? CONULARIA, Miller. 
Etymology, conulus, a little cone. 
Type, C. quadrisulcata, Fig. 144. 
Shell four-sided, straight, and_ tapering, the angles 
Y grooved, sides striated transversely, apex partitioned 
off. 
Fossil, 40 species. Silurian—Carb. North America, 
- Europe, Australia. 
Sub-genus.  Coleoprion (gracilis), Sandberger ; 
Devonian. Germany. Shell round, tapering, sides- 
obliquely striated; stric alternating along the dorsal 
line. 
Fig 144.4 EvRYBIA, Rang. 1827. 
Hiymology, Hurybia, a sea-nymph. 
Synonym, Theceurybia, Bronn. 
Example, H. Gaudichaudi, Pl. XIV., Fig. 37 (after Huxley). 
Animal globular ; fins narrow, truncated, and notched at the 
ends, united ventrally by a small lobe (metapodium); mouth 
with two elongated tentacles, behind which are minute eye- 
peduncles and a two-lobed rudimentary foot (mesopodiwm) ; body 
enclosed in a cartilaginous integument, with a cleft in front, 
into which the locomotive organs can be retracted. Lingual 
teeth, 1.0.1. 
The animal has no proper gill, but Mr. Huxley has observed 
two ciliated circles surrounding the body, as in the larya of 
Pneumodermon. 
Distribution, 4 species. Atlantic and Pacific. 
Sub-genus. Psyche, Rang. (Halopsyche, Bronn.) P. globulosa, 
* Creseis Sedgwicki, Forbes, is an orthoceras with very thin septa, belonging to the 
game group with (Conularia) teres, Sby. Tentaculites, Schl. is annellidous. (Salter.) 
j Carboniferous limestone, Brit. Belgium. 
§ This name had been previously employed for four different genera of plants and 
animals. 
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