TO GEOLOGY. 95 
Two species only of this genus seem to have been ob- 
served in England, neither of which belongs to the London 
Clay. The clathrata has been found in the Great Oolite— 
the greca in the Crag. Inthe Tertiary Tables of M. Des- 
hayes we have eight species, four of which are from the 
Paris basin. From the Maryland deposit we have two 
species, F. redimicula (Say), and F. greca (Lamarck), 
specimens of both of which may be seen in the Academy 
of Natural Sciences. Of the greca being the anologue of 
the West India species I have great doubt. 
GENUS HIPPONIX. Defrance and Blainville. 
H. pygmea. Plate 3. Fig. 75. 
Description. Shell subrotund, obliquely conical, closely 
ribbed ; apex straight, pointed ; cicatrices impressed ; mar- 
gin entire. 
Long. diam..2, Transv. diam. 3-20ths, Height nearly .J,ofan inch. 
Figure magnified. 
Observations. This interesting little shell has a strong 
resemblance in form to H. cornucopia (Defrance and Blain- 
ville), Pileopsis cornucopia (Lamarck). I have determined 
to place it in that genus in consequence of its possessing 
the horse shoe shaped cicatrix mentioned by Blainville,* 
although I have not seen it attached to any support. 
* Manuel de Malacologie, &c. p. 507. 
