MUSEUM OF COMPARATIVE ZOOLOGY. 191 



Adult specimens have four or five well-developed denticles inside the outer lip, 

 and a larger one at the beginning of the canal opposite a tooth-like callus on the 

 pillar. The other characters are much like those of A. Raveneli. 



Among the widely distributed forms which appear in deep water on our 

 eastern coast is the Astyris rosacea of Gould. After examining a very fine 

 geographical series, I have been unable to separate the Greenland shells from 

 those of Norway, New England, or Alaska, all the characters which have been 

 relied upon as diagnostic being mutable and interchangeable. The name 

 Holbbllii of Mdller will therefore fall into synonymy. However, the slender 

 shell called diaphana by Prof. Verrill I regard as entitled to specific rank, 

 although the spiral lines are quite variable, and are distinctly visible on 

 some of the specimens of diaphana received from him. The nucleus, as stated 

 by him, is more compact, but this is a difference which alone could hardly be 

 regarded as of specific value. The shell, however, has other characters, which 

 are enumerated below. 



Before leaving this topic, I may mention as an addition to our fauna the 

 Astyris fusiformis Orbigny, an Antillean form, which was obtained in 6-10 fms. 

 at Turtle Harbor, Florida, by that zealous collector, Dr. W. H. Rush, U. S. N. 



Astyris diaphana Verrill. 



Plate XXXV. Fig. 9. 



Astyris rosacea (pars) Verrill, Proc. U. S. Nat. Mus., III. p. 408 (non Gould). 

 Astyris diaphana Verrill, Trans. Conn..Acad., V. p. 513, pi. lviii. fig. 2, 1882. 



Shell of the form and general appearance of A. rosacea Gld. (Holbollii Moll.), 

 but more slender, with a prominent swollen varix behind the outer lip, which 

 is slightly thickened and finely lirate within. In front of the varix the suture 

 descends quite sharply, or bends forward. The nucleus is white and like that 

 of A. profundi, and there are five other whorls, which are marked with ob- 

 scure elevated spiral lines, with irregular interspaces, which look as if scratched 

 with a pin on the inside of the shell and showing through. These give the 

 surface, which is polished and lightly marked with lines of growth, a malleated 

 appearance. The anterior half of the last whorl is grooved, the grooves being 

 stronger and wider in proportion as they are anterior; the interstitial eleva- 

 tions on the canal are like rounded threads. The suture is distinct but not 

 channelled; on some of the whorls it is accompanied by a fine groove just in 

 advance of it. The general color of the shell is pale straw-color, and the epi- 

 dermis is not hispid like that of rosacea. Lon. of shell, 9.0; of last whorl, 5.6; 

 of aperture, 4.0; max. lat. of shell, 3.3 mm. 



Habitat. U. S. Fish Commission Stations 876, off Newport, R. I., in 65 

 to 487 fms., and 2399, in 196 fms., mud, between the Mississippi delta and 

 Cedar Keys, Florida, bottom temperature 51°.6 F. 



It recalls A. profundi Dall, but is more elegant, slender, and has more 

 rounded outlines. There are no traces of transverse ribbing. 



