352 CADULUS-POLYSCH1DES. 



it is very near Ball's C. amiantus, but that species is stated to have 

 "" both orifices circular and not notched," and with a length of 5'75 

 it has a greatest diameter of 1/4 mill., while in a specimen of our 

 species 5*6 in length, the greatest diameter is only 1*0 mill. In 

 other words, the greatest diameter of amiantus is contained 4*1 

 times in the length of the shell, and that of tetrodon 5'6 times. The 

 slender specimens of amiantus reported from off Cape Florida by 

 Dall may be individuals of our species with the teeth broken off. 

 Types are No. 71,070 coll. Acad. Nat. Sci. Phila. 



C. CAROLINENSIS Bush. PI. 25, fig. 64 ; pi. 30, figs. 24, 25, 26, 27. 



Shell of medium size, semitransparent (perfectly fresh specimens 

 are almost transparent and glassy, showing the animal quite dis- 

 tinctly), very glossy, bluish-white, nearly circular throughout its 

 entire length. Greatest diameter at about the anterior third, 

 diminishing moderately to the round, very oblique anterior aper- 

 ture, and backward to the posterior end, at first very gradually and 

 further back more rapidly. Curvature well marked in some speci- 

 mens, slightly in others, nearly uniform along the convex side ; the 

 outline of concave side somewhat, though but slightly, convex along 

 the swollen half or more of the length, concave posteriorly. Great- 

 est diameter contained 51 to 6'6 times in the length of the shell. 

 Aperture oblique, subcircular, the peristome inflexed along the con- 

 vex margin. Posterior aperture very small, round and with four 

 small distinct notches, two on each side ; teeth very short. 



Length 9'8, diam. at aperture 1 x 1, at greatest inflation 1*6 x 

 1.6, at apex 0*52 x 0'6 mill. 



Length 9'7, antero-posterior diam. at aperture 1*0, at greatest in- 

 flation 1*45, at apex 0'5 mill, (specimens). 



Length 9*5, greatest diameter about 2*0 ; anterior aperture 1*0, 

 and posterior aperture 0'4 mill. (Bush). 



Cape Hatteras, very abundant in 7-48 fms. (U. S. Fish Commis- 

 sion, Rush) ; Old Providence in 382 fms. (Dall) ; Vera Cruz, Mex- 

 ico (Heilprin & Baker). 



C. carolinensis BUSH, in Verrill, Res. Expl. Albatross, 1883, Ann. 

 Rep. Commissioner Fish and Fisheries for 1883, art. xvi, p. 587, 

 (1885) ; Trans. Conn. Acad., vi, p. 471, pi. 45, f. 19 (June, 1885). 

 DALL, Rep. Blake Gastr. & Scaph., p. 430 (1889) ; Bull. U. S. 

 Nat. Mus., No. 37, p. 78. 



