1849.] SHARPE ON THE SECONDARY ROCKS OF PORTUGAL. 179 



dista^ in which arrangement I cannot follow him, as this one charac- 

 ter appears outweighed by all the other analogies which connect the 

 Caprinidce with the Chamacece. To show the lobes of the shell and 

 the longitudinal tubes as far as possible, sections are added to the 

 figures of the species, and the fig. 2. Plate XVI. shows a fore-short- 

 ened view of the upper valve of Caprinida Boissyi nearly perfect. 



The outer layer of shell is very thin, and is rarely preserved in the 

 specimens from Lisbon : it seems to be of a different structure from 

 the inner shell, as is the case in Die eras ; but the bad condition of 

 the specimens prevents my speaking with certainty on this head. 



The hinge has not been seen, but it may be inferred from the strong 

 plate or column a of the figure just quoted, which runs down the 

 whole valve, that, as in Chama and Capi^ina, the principal feature of 

 the hinge was a very strong tooth. The ligament appears to have 

 been external and to have lain in the longitudinal furrow h of the 

 same figure, in which it resembles that of the Chamacece : this liga- 

 mental furrow is well shown in the plates 536. figs. 2 and 3, 538. fig. 

 1, and 540. fig. 1, of the ' Paleontologie Fran9aise.' 



All the species of CaprinidcB here described were found together 

 in the hippurite limestone of Lisbon, contemporary with our chalk, and 

 they all fall under M. d'Orbigny's definition of Capri7iula (Comptes 

 Rendus, 16 Aug. 1847). The genus Caprina appears distinct from 

 CaprinulUi but there hardly seem characters sufficient to distin- 

 guish Caprinella from the last-named genus ; and the whole family 

 appears to belong, together with Biceras, to the Chamacece, 



Caprinula Boissyi, D'Orb. T. Cret. 540. {Vost, Pl. XVI. fig. 1, 



2, & 3.) 



Shell very inequivalve, the lower valve spiral and ending in a blunt 

 apex, with one or two whorls, marked by rough lines of growth ; 

 otherwise smooth : upper valve straight, covered with strong longi- 

 tudinal flutings which are irregularly broken by the concentric lines 

 of growth. A deep external channel marks the place where the liga- 

 ment has interrupted the growth of the shell. 



Very abundant in the hippurite limestone at Lisbon. 



In very large specimens the spire is 9 inches across and the straight 

 valve 9 inches long. — N.B. My specimens all show a blunter apex 

 than M. d'Orbigny's figure. 



Plate XVI. fig. 1. A specimen with both valves nearly perfect, 

 except that the lower valve has lost its surface. 



Fig. 2. A siliceous specimen of the upper valve cleaned by acid : 

 the edge is partially broken away, but the plates which divide the 

 body of the animal into lobes, and the tubes which penetrate the walls 

 of the shell are well seen. The thick plate a would probably end in 

 a strong tooth similar to that in Chama, The external furrow h has 

 held an external ligament, as in Chama^ Isocardia^ &c. The speci- 

 men is 6 inches long. 



Fig. 3. A section of the valve, showing the tubes in the wall of 

 the shell and the lobes of the body of the mollusk. 



