886 MANUAL OF THE MOLLUSCS, 
CHONETES, Fischer. 
Example, CO. striatella, Pl. XV., Fig. 29. 
Etymology, chone, a cup. 
Shell transversely oblong, with a wide and straight hinge-line; 
area double; valves radiately striated, articulated; hinge-margir 
of ventral valve with a series of tubular spines; fissure covered; 
interior punctate-striate; vascular impressions (v) very small. 
(Davidson. ) 
Fossil, 47 species. Silurian—Carboniferous. Europe, North 
America, Fulkland Islands. 
Dorsal valve. Fig. 192. Ventral valve.* 
FAMILY VI.—CRANIADA, 
Shell orbicular, calcareous, hinge-less ; attached by the umbo, 
or whole breadth of the ventral valve, rarely free; dorsal valve 
limpet-like; interior of each valve with a broad granulated 
border; disk with four large muscular impressions, and digitated 
yascular impressions; structure punctate. 
Animal with free spiral arms, directed towards the concavity 
of the dorsal valve, and supported by a nose-like prominence in 
the middle of the lower valve; mantle extending to the edges 
of the valyes, and closely adhering; its margins plain. 
(Fig. 195.) 
CRANIA, Retzius. 
Etymology, kraneia, capitate. 
Type, Anomia craniolaris, L. 
Examples, C. Ignabergensis, Pl. XY., Fig. 30. C. anomala, 
Figs. 193—195. 
Synonyms, Criopus, Poli. Orbicula (anomala), Cuvier, 
~=O. Norvegica, Lam. 
* Interiors of two sp, of Chonetes, from Nehou and the Eifel, after Davidson: 4, 
adductor ; c, cardinals. 
