132 BULLETIN 111, UNITED STATES NATIONAL MUSEUM. 



Watson's mention of a "chipped" apical rim makes doubtful the 

 position of the species under Gadila. 



It is less swollen than Cadulus rastridens. The swelling is more 

 median and without the bluntly angulated equator of the latter. 



The mention of a longitudinal sculpture does not set this apart 

 from other species of Cadulus, for the suggestion of a shadow of 

 sculpture when viewed in oblique light, may be detected in some 

 specimens of all species, particularly if the imagination be as care- 

 fully focussed as the microscope. 



I am unable to refer with satisfying assurance any shells in the 

 Museum collection to this very conventionally shaped little Cadulus. 



CADULUS (GADILA) RASTRIDENS Watson. 



Plate 19, fig. 1. 



1879. Cadulus rastridens Watson, Journ. Linn. Soc. London, vol. 14, p. 525. 

 1885. Cadulus rastridens Watson, Challenger Report (Scaphopoda), p. 19, pi. 3, 



fig. 3. 

 1898. Cadulus (Gadila) rastridens, Pilsbry and Sharp, Tryon's Man. Conch, 

 vol. 16, p. 174, pi. 25, fig. 62. 



The shell is very small, slightly compressed, narrow, "bent," with 

 a swelling at about the anterior three-eighths which is faintly keeled 

 at the equator. Tiie anterior aperture is not oblique and is rather 

 large. Tlie convex side exhibits a rather straiglit outline from the 

 apical end to the equator; thence, at an angle, again rather straight 

 to the anterior aperture. The concave side describes a shallow arch 

 with a very slight convexity at the equator. The apical orifice is 

 relatively large and round. No apical features are mentioned besides 

 the rim being "less chipped than the mouth (anterior aperture)." 

 Measiu'ements are: 



Length, 3 mm.; diameter, 0.6 mm.; anterior aperture, 0.38 mm.; 

 apical aperture, 0.25 mm. (Watson). 



The type is in the British Museum, taken at Challenger Station 24, 

 off Culebra Island, in 390 fathoms, bottom of Pteropod ooze. 



In the museum collection are topotypes from author. Cat. No. 

 118774, U.S.N.M. Also a lot of four specimens. Cat. No. 108280, 

 U.S.N.M., from the U. S. B. F. Station 2415, off Georgia, in 440 

 fathoms, bottom of sand, 45.6° F. Also a lot of 85 specimens. Cat. 

 No. 108169, U.S.N.M., from the U. S. B. F. Station 2668, off Fernan- 

 dina, Florida, in 294 fathoms, bottom of gray sand and dead coral, 

 temperature 46.3°; also 35 specimens. Cat. No. 108168, U.S.N.M., 

 from the same station. 



The "bent" appearance is the result of the break at the equator in 

 the outline of the convex side, forming an angle between two rather 

 straight lines. In most Caduli the outline of the convex side is more 

 arched and the "break" is less apparent. The lack of obliqueness 

 in the anterior aperture is striking. 



