CHAMIDA. 201 
becomes detached, as the large specimens are found imbedded 
with the spire downwards.—SAEMANN. 
Lycopus, Schafhaeutl, 1863. Shell inequivalve, oblong, mod- 
erately tumid, with large incurved and rather approaching 
beaks; of solid structure and concentrically costate. In the 
place of the hinge there seems to be in the left valve a large 
hinge-plate, the anterior portion of which is partially elevated 
and prolonged into a transverse tooth, and the posterior 
depressed, probably for the reception of the tooth of the other 
valve. From the posterior part a rib runs internally up to the 
umbones, and there is also a posterior elongated tooth present 
almost parallel to the margin of the shell. One species, L. cor, 
is figured and described from an Alpine limestone bed, probably 
lower secondary. 
Caprotina, d’Orbigny, 1842. 
Distr.—Fossil, 10 sp. Upper Greensand; France. C. striata, 
d’Orb. (exvii, 14,15). C. quadripartita (exviii, 21). 
Shell composed of two distinct layers; valves alike in struc- 
ture, dissimilar in sculpturing; ligamental groove slight ; 
cartilage internal; right valve fixed, striated or ribbed, with one 
narrow tooth between two deep pits, several pits on each side of 
the ligamental inflection, posterior adductor supported by a 
plate; free valve flat or convex, with a marginal umbo; teeth 
two, very prominent, supported by ridges (apophyses) of the 
adductor muscles, the anterior tooth connected with a third 
plate which divides the umbonal cavity. 
The smaller Caprotinze occur in groups, attached to oyster- 
shells; their muscular ridges are much less developed than in 
the large species. C. costata is like a little Radiolite. 
CAPRINELLA, d’Orbigny, 1847. 
Syn.—Caprinula (Boissit), d’Orbigny, 1847. Ichthyosarco- 
lithes, Desm. ?Chaperia, Mun.-Chal., 1873. j 
Distr.—Fossil, 6 sp. Cretaceous; France, Portugal, Sicily. 
C. Aiguilloni (exviii, 18). 
Shell fixed by the apex of the right valve, or free; composed 
of a thick layer of open tubes, with a thin compact superficial 
lamina; cartilage internal, contained in several deep pits; 
umbones more or less camerated; right valve conical or elon- 
gated, with a ligamental furrow on its convex side, and furnished 
with one strong hinge-tooth supported by an oblique plate; left 
valve oblique or spiral, with two hinge-teeth, the anterior 
supported by a plate which divides the umbonal cavity length- 
wise. 
In C. triangularis, Desm. (exviii, 22, 23), the umbonal cavity 
of the spiral valve is partitioned off at regular intervals; the 
_ length of the water-chambers is sometimes 3} inches, and of 
14 
