NEW MOLLUSKS OF THE GENUS ACLIS FROM THE NORTH 



ATLANTIC. 



By Paul Bartsch, 



Assistant Curator, Division of Mollusks, U. S. National Museum. 



This little paper embraces descriptions of a number of new forms 

 which were dredged in rather deep water off the Atlantic coast of 

 North America by Dr. W. H. Rush, U. S. N., and the U. S. Bureau 

 of Fisheries steamers Fish Hawk and Albatross. The one coming 

 from New England has been known for some time, but has been 

 confused with the European Aclis walleri Jeffreys, under winch name 

 it has appeared in lists. In this connection, it would be well to 

 mention that Aclis striata Verrill is not an Aclis, but a Pyramidellid, 

 belonging to the genus Odostomia, subgenus Menesilio. 



ACLIS DALLI, new species. 

 Plate 59, fig. 1. 



Shell slender, very elongate-conic, milk-white, vitreous. Nuclear 

 whorls not differentiated from the rest. Early post-nuclear whorls 

 well rounded; the later half strongly inflated ; all strongly appressed 

 at the summit, the appressed portion appearing as a slightly differen- 

 tiated color band at the summit of the whorls. The entire surface 

 of the shell is sculptured only by exceedingly fine incremental lines. 

 Sutures very strongly constricted. Periphery of the last whorl and 

 the moderately long base well rounded, smooth. Aperture large, 

 somewhat effuse anteriorly; posterior angle obtuse ; outer Up thin and 

 semi transparent; columella moderately long, curved and reflected. 



The type (Cat. No. 94288, U.S.N.M.) was dredged by Doctor Rush 

 at his station 34 in 780 fathoms on coral mud bottom off Cuba. It 

 has 17 whorls and measures: Length 7.8 mm., diameter 1.7 mm. 



Named for Dr. W. H. Dall. 



ACLIS CUBANA, new species. 

 Plate 59, fig. 2. 



Shell small, slender, elongate-conic, milk-white. Nuclear whorls 

 two, the first very much inflated, strongly rounded, and larger than 



Proceedings U. S. National Museum, Vol. 40— No. 1829. 



435 



