CHAMIDiE, 201 



becomes detached, as the lai'ge specimens are found imbedded 

 with the spire downwards. — Saemann. 



LYCODUS, 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 figui'ed and described from an Alpine limestone bed, probabl}"- 

 lower secondary. 



Caprotina, d'Orbigny, 1842. 



Distr. — Fossil, 10 sp. Upper Grreensand; France. C. stiHata, 

 d'Orb, (cxvii, 14, 15). G. quadripartita (cxviii, 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 Caprotiute 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'Orbignjr, 1847. 



Si/n. — Caprinula (Boissii), d'Orbigny, 1847. Ichth3^osarco- 

 lithes, Desm. ? Chaperia, Mun.-Chal., 1873. . 



Distr. — Fossil, 6 sp. Cretaceous; France, Portugal, Sicily. 

 C. Aiguilloni (cxviii, 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. (cxviii, 23, 23), the umbonal cavit}' 

 of the spiral valve is partitioned oft* at regular intervals ; the 

 length of the water-chambers is sometimes 3| inches, and of 

 14 



