102 BULLETIN 111, UNITED STATES NATIONAL MUSEUM. 



CADULUS (POLYSCHIDES) CAROLINENSIS Bush. 



Plate 17, figs. 6, 7. 



1885. Cadulus carolinensis Bush, Verrill's Article in Report of Com. of Fish and 

 Fisheries for 1883, p. 587. 



1885. Cadulus carolinensis Bush, Trans. Conn. Acad. Arts and Sci., vol. 6, pt. 2, 

 p. 471, pi. 45, fig. 19. 



1889. Cadulus carolinensis, Dall, Bull. Mus. Comp. Zool., vol. 18, p. 430 (exclud- 

 ing Old Providence record). 



1889. Cadulus carolinensis, Dall, Bull. 37, U. S. Nat. Mus., p. 78, in part, pi. 41, 

 fig. 19. 



1898. Cadulus (Polyschides) carolinensis, Pilsbry and Sharp, Tryon's Man. 

 Conch., vol. 17, p. 152, pi. 25, fig. 64; pi. 30, figs. 24-27. 



1903. Cadulus carolinensis, Dall, Bull. 37, U. S. Nat. Mus., p. 78, in part, pi. 41, 

 fig. 19. 



The shell is of medium size, moderately curved, with its greatest 

 diameter about one-fourth distance from the anterior aperture. There 

 is no bulbous or local swelling. The convex side shows a fairly even 

 arc, but flattened and accelerated from the point of maximum diam- 

 eter to the anterior aperture, which is very oblique, and with a 

 smooth rounded peristome. The concave side shows an even, gentle 

 curvature through its posterior half, and thence it is rather straight, 

 showing scarcely any convexity in its outline at the point of greatest 

 diameter. The apical opening is very small and is modified by four 

 shallow slits or notches, producing between them four short flat- 

 topped lobes, one dorsal, one ventral, and two lateral. These apical 

 features are often confused by the breaking, wearing down, or by 

 some injury to the lobes. The slits are shallower than those in the 

 other species already referred to under Polyschides, and show an 

 intermediate stage between Polyschides and Platyschides. Measure- 

 ments are: 



Length, 9.S mm.; maximum diameter, 1.6 mm.; anterior aperture, 

 1 mm.; apical aperture, .52 by .6 mm. (type). 



Length, 9.7 mm.; maximim diameter, 1.45 mm.; anterior aper- 

 ture, 1 mm.; apical aperture, 0.5 mm. (Pilsbr}^). 



Length, 9.5 mm.; maximum diameter, 2 mm.; anterior aperture, 

 1 mm.; apical aperture, 0.4 mm. (Bush). 



The type, Cat. No. 35811, U.S.X.M., was dredged at the U. S. B. 

 F. station 2114 off Hatteras, in 14 fathoms, bottom of mud and 

 broken shells, temperature 72° F. 



This is a very abundant species about the Hatteras region in snal- 

 low water. Records show extremes of .3 fathoms in Cape Lookout 

 Bight to 87 fathoms off Cape Hatteras. It is less abundant farther 

 south. 



The shell is easily to be distinguished irom Cadulus quadridentatus 

 by its greater inflation and its shallower apical slits, and from C 

 tetrodon by its larger size. There are among the many National 



