/ 
CUNCHIFERA. 417 
Ambonychia (bellistriata), Hall, 1847. Nearly equivalve, 
gibbose, oblique, obtusely winged. A. vetusta (Inoceramus, 
Sby.) is concentrically furrowed; the right valve has a small 
anterior ear (usually concealed) separated by a deep and narrow 
sinus. Jfossil, 12 species. Lower Silurian — Carb. United 
States, Hurope. 
? Cardiola (interrupta), Broderip, 1844. LEquivalve, gibbose, 
obliquely oval, radiately ribbed ; beaks prominent; hinge-area 
short and flat. fossil, 17 species. Upper Silurian — Dey. 
United States, Europe. 
? Hurydesma (cordata), Morris; Devonian? New South Wales. 
Shell equivalve, sub-orbicular, ventricose, very thick near the 
beaks; lhgimental area long, wide, sub-internal; byssal groove 
close to the umbo; right valve with a large, blunt hinge-tooth ; 
adductor impression single, placed anteriorly; pallial line dotted. 
Pterinea (levis), Goldf. 1832. Shell thick, rather inequivalve, 
very oblique and broadly winged ; beaks anterior; sinus shallow ; 
_ hinge-area long, straight, narrow, striated lengthwise; ante- 
rior teeth few, radiating; posterior teeth laminar, elongated ; 
anterior (pedal) scar deep, posterior (adductor) impression large, 
very eccentric. Jossil, 32 species. Lower Silurian — Carb. 
United States, Europe, Australia. Pteronites (angustatus) 
M‘Coy, 1844, is thinner and has the teeth, &c., less developed. 
Monotis, Bronn, 1830. M. Salinaria, Schl. Trias, Hallein. 
Obliquely oval, compressed, radiated; anterior side short, 
rounded ; posterior slightly eared. 
Synonym, ? Halobia (salinarum) Br. 1830. Trias, Hallstadt. 
Semi-oval, radiated, compressed, with a shallow sinus in front ; 
- hinge-line long and straight. 
PosIDONOMYA, Bronn. 
Synonym, Posidonia, Br. 1838 (not Kénig). Poseidén, Nepture. 
Type, P. Becheri, Pl. XVI., Fig. 22. 
Shell thin, equivalye, compressed, earless, concentrically 
furrowed; hinge-lne short and straight, edentulous. 
Fossil, 50 species. Lower Silurian — Trias. United States, 
Europe. 
P AVICULO-PECTEN, M‘Coy, 1852. 
Type, Pecten granosus, Sby. Min. Con. t. 574. 
Shell inequivalve, sub-orbicular, eared; hinge-areas flat, with 
several long, narrow cartilage furrows, slightly oblique on each 
side of the umbones ; right valve with a deep and narrow byssal 
sinus beneath the anterior ear; adductor impression large, 
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