GASTEROPODA. 
Excample, P. bilobatum. Upper Lias, Normandy. Fig. 11. 
Calcareous plates nearly circular or transversely oval ; ante< 
Fig. 11. 
rior border rounded, posterior produced and truncated ; concave 
above and flattened below; the two faces have one-half smooth 
and the other concentrically striated in an inyerse direction 
to each other. 
fossil, 3 or 4 species. Up. Lias— Cor. Rag. England; 
Normandy ; Wurtemberg. 
CLASS II.—GASTEROPODA. 
OrDER I.—PROSOBRANCHIATA. 
FAamILty II.—MuRiIcip# (see p. 212, &c.),. 
b 
The genera included in this family are :— 
MUREX, TYPHIS, PISANIA, TROPHON, FASCIOLARIA, TURBI< 
NELLA (Cynodonta, Latirus, Lagena), Eusus (Clavella, Chryso- 
domus, Pusionella, Tritonidea), FuLG@UR, COMINELLA, MyrRIs- 
TICA, and LACHESIS 
ANAcHIS, H. and A. Adams. 
Type, Columbella scalarina, Sowerby. 
Shell like Columbella; operculum elongated, unguiform, 
nucleus terminal, haying close analogies with Pisania.. 
Distribution, 27 species. Tropical America. 
PTYCHATRACTUS, Stimpson, 1865. 
Etymology, ptych, a fold; atractus, a spindle. 
Type, Fasciolaria ligata, Mighels and Adams, Deep water; 
United States. 
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