Navicuiacea.] infuaorial akiMalcules. 459 



semi-lunate; (%s. 19G, 197, 198.) Found living on aquatic plants, 

 and fossil at Cassel, San Eiore, and Justraba, in Hungary. Length 

 1.430th. to 1-11 50th. 



CoccoN-EUX ciJmbifo>'me. — Slender, lanceolate: extremities subacute ; 

 on the other side, linear-oblong, truncate-obtuse; transverse striae 

 sixteen in 1-1 200th. Stipes filiform, obsolete, (imperceptible indi- 

 vidually) in the intricate, jolly-like mass they form. Common length 

 1- 500th to 1-1 50th. (P. 15, f. 46.) 



C. gihhum. — Semi-oval; transverse striae rather fine ; slightly con- 

 stricted at the ends which are produced and punctate ; stipes branching 

 dichotomously ; rather stout. Length l-480th. Alive and fossil 

 (P. 16, f. 10.) 



C. asperum. — Habit and dimensions of C. lanceolatum, but with 

 the striae denticulate, or interrupted by dots (puncta.) Length 

 l-288th. Fossil in France. 



C. Gf'oecum. — Habit of C. Cistula, with stronger, but fewer stiiae ; 

 only twelve to thirteen in l-576th. Length l-576th. 



C. Arous. — Linear ; ciu'ved on each side, striated and obtuse ; 

 centre of ventral surface not tumid. New York. 



C. (?) acutum. — Small, slender, slightly bent, smooth (?), acute at 

 each end ; on ventral surface, slightly turgid at centre. Habit of 

 Na/vicula Amphioxys. 



C. corntdiim. — Larger, striated, lunate ; ventrally gradually 

 tumid at centre ; extremities tapering gently, and obtuse. 



C. gracile. — Linear-lanceolate ; straight or slightly curved ; convex 

 on dorsum ; plane (flat) on ventral ; ends slender, subacute, 



C. Leptoceros. — Long, slender, slightly ciu'ved, venter abruptly 

 tumid at its centre ; apices attenuate. 



C Lumda. — Semi-orbicular; minutely striated; venter plane, 

 dorsum convex ; cornua (Ixoms, elongated ends) wanting. Approaches 

 C. Cistula. 



C. Mexicanum. — Large, striated, thick, lunate ; venter slightly 

 tumid; ends (cornua) obtuse, and but little produced; eighteen 

 striae in l-1152ud., but distinctly and elegantly granular. Length 

 1-2 16th. Mexico. 



C. sessile. — Resembles C. gihbum, of which it is but a variety, 

 diflfering by being attached without a stalk. 



H H 2 



