CRANIA.—Ptate I. 
Species 4. (Mus. Cuming.) 
CRANIA ANOMALA. Cran. testa valvd inferiore subquadra- 
to-orbiculari, posticé subtruncatd, cicatricibus posticis 
magnis, ovatis, in centrum fere coalescentibus, rostello 
obtuso, disco palmato-radiato, limbo antico incrassato, 
granulato ; valvd superiore tenuiculd, nunc levigatd, 
nune angulosa, rufescente-brunneo tinctd, vertice sub- 
acute uncinato, cicatricibus posticis magnis. 
ANOMALOUS CRAnNIA. Shell with the lower valve 
somewhat squarely orbicular, posteriorly slightly trun- 
cated, posterior scars large, ovate, almost coalescing 
in the centre, rostellum obtuse, disk palmately radi- 
ate, anterior rim thickened, granulated; upper valve 
rather thin, sometimes 
THE 
smooth, sometimes rather 
rough, stained with reddish-brown, vertex rather | 
sharply hooked, posterior scars large. 
Patella anomala, Miiller, Zool. Dan. vol. 1. p. 14. pl. 5. 
f. 1 to 7. 
Anonia craniolaris, pars, Linnzeus. 
Patella distorta, Montagu. 
Patella Kermes, Humphrey. 
Orbicula Norwegica, Lamarck. 
Crania personata, Lamarck. 
Crania Norwegica, Sowerby. 
Criopus anomalus, Fleming. 
Crania anomala, Lovén. 
Hab. North Atlantic, from Spitzbergen to Vigo Bay. 
The typical form of this species is orbicular, slightly 
truncately squared on the posterior side, with the vertex 
| produced into a small and rather sharp hook a little pos- 
terior to central. On the stone represented in our plate, 
there are twelve specimens attached. The lowest, resting 
by itself on a flat surface, undisturbed in growth by any 
surrounding obstacles, is of the symmetrical typical form 
just described ; on the left, as the specimens approximate 
and encumber one another, they become distorted ; on the 
edge of the stone to the extreme left, the shell, from its 
declivitous position, acquires an abrupt convexity. 
Professor Suess has observed that Crania anomala ranges 
| along the Atlantic seaboard, between Spitzbergen and 
Vigo Bay, in company always with Zerebratula (Lerebra- 
tulina) caput-serpentis, but does not extend its range with 
that species to North America or the Mediterranean. 
