EAST AMERICAN SCAPHOPOD MOLLUSKS. 135 



slight concavity near each end. The hiteral outlines are rather 

 straight, with an angle at the equator. The cylinder is hardly flat- 

 tened. The anterior aperture is oblique; the apical orifice is round 

 and of about half the diameter of the larger aperture, and carries a 

 callous rib just within the opening. The apical features are not clearly 

 defined, but are probably simple. 



The type, Cat. No. 161581, U. S. N.M., measures — length, 2 mm.; 

 diameter, 0.5 mm.; anterior aperture, 0.3 mm.; apical aperture, 0.15 

 mm. It was dredged at the U. S. B. F. Station 6062, in Mayaguez 

 Harbor, Porto Rico, in 25 fathoms, bottom of sand, mud and shells, 

 temperature 75.8° F. 



In the National Museum collection are also the following lots: 

 three specimens, Cat. No. 323014, U.S.N.M., taken at the U. S. B. F. 

 Station 2315, off Key West, Fla., in 37 fathoms, bottom of coral; 

 one specmien. Cat. No. 314817, U.S.N.M., taken at Eolis Station 68, 

 off Miami, Florida, in 45 fathoms; one specimen, taken off the Laza- 

 retto, Barbados, in 80 fathoms, by the Iowa State University Expe- 

 dition at their station 86, seems quite typical, although the length is 

 about 2.25 mm. 



This little mite of a shell is the smallest of this group of very small 

 forms, and is one of the smallest of all mollusks. Although its meas- 

 urements in fractions of millimeters do not seem to warrant it, yet 

 when laid side by side with Cadulus minusculus it seems to be hardly 

 half as large. 



CADULUS (GADILA) SUBULA, new species. 



Plate 19, fig. 5. 



The shell is very small, exceedingly slender, moderately curved, 

 and very slightly compressed. Its equator is median and is slightly 

 swollen. The cylinder is a little flattened on its convex side just 

 back of the anterior aperture. The convex outline is regularly arched 

 with a scarcely perceptible modification at the equator. The con- 

 cave outline has a convexity at the point of maximum diameter and a 

 slightly concave arc above and below. Viewed on the concave face 

 the lateral outlines present two almost parallel lines, somewhat de- 

 flected apart at the equator. The anterior aperture is round, oblique, 

 and has a rounded smooth peristome. The apical orifice is a little 

 flattened into an oval shape; and is not much smaller than the other 

 aperture. 



The type. Cat. No. 323113, U.S.N.M., measures ^length, 3.50 mm.; 

 diameter, 0.5 mm.; anterior aperture, 0.35 mm.; apical aperture, 

 0.275 mm. It was dredged by the Albatross at the U. S. B. F. Sta- 

 tion 2352, off Bahia Honda, Cuba, in 463 fathoms, bottom of white 

 coral mud, temperature 45° F. It is selected from a unique lot of 

 two specimens. 



