MUSEUM OF COMPARATIVE ZOOLOGY. 101 



has the same distribution, hut is more abundant. It is a good and well-marked 

 species. Of the group having a polygonal cross-section and translucent glassy 

 shells on which the sharp transverse ribs run from canal to nucleus without 

 a break across all the whorls, there are several forms. These perhaps should 

 be referred to a particular section of typical Mangilia rather than to any 

 part of Cythara, but I will mention them here. Mangilia psila Bush, when 

 fresh, is pink-tipped and transparent. It is the northern representative of 

 M. lanceolata Adams, which in the Antilles grows much larger and has spiral 

 color lines. M. muricoides Adams, a species of the same general characters, is 

 larger and stouter. I have seen in only from Barbados. 



Cythara Bartlettii n. s. 



Plate XII. Fig. 6. Plate XIV. Figs. 5, 8. 



Shell oval, spire rather acute ; nucleus glassy, dark Lrovvn, inflated, of a 

 whorl and a half, followed by five normal whorls ; color pale yellowish, with 

 irregular touches of pale brown especially on the varix ; spiral sculpture of 

 numerous fine subequal rounded little-raised threads, with wider interspaces, 

 covering the whole shell and stronger on the canal; transverse sculpture of 

 (1) extremely fine close parallel hardly raised incremental lines, visible only 

 with the glass, and traversing the spiral interspaces with great regularity and 

 perfect uniformity ; (2) on the antepenultimate whorl about twenty narrow, 

 little raised, long rounded riblets, starting from the suture and fading away on 

 the base ; the spirals run smoothly over the ribs ; fasciole only visible in the 

 curve of the incremental lines; notch narrow, rounded, not deep ; outer lip re- 

 inforced in the adult by a rather thick rounded varix from which the thin sharp 

 edge of the lip stands out prominently, arched forward in the middle, and is 

 not contracted for the canal ; inner lip simple, pillar obliquely trimmed off in 

 front, otherwise straight ; canal short, wide, not differentiated from the aper- 

 ture. Max. Ion. of shell, 10.0 ; of last whorl, 7.5 ; lat. of shell, 4.75 mm. 



Habitat. Off Havana, in 127 to 450 fms.; Barbados, 100 fms. ; Station 132, 

 near Santa Cruz, in 115 fms., rocky bottom, temperature 65° F. ; also at Key 

 West, between tides, on algoe, H. Hemphill. 



The sculpture of this form, when fresh, is very inconspicuous, and the shell 

 looks almost smooth. It is perhaps the smoothest of the group, and may be 

 distinguished in this way from the others. 



The young shell has very much the aspect of some of the northern species 

 of Bela. 



Cythara cymella n. s. 



Plate XII. Fig. 4. 



Shell long, slender, subhyaline, polished, having a small subglobular, vitre- 

 ous, tilted nucleus of one and a half whorls, and five and a half subsequent 

 whorls ; color translucent, with a faint yellowish band in front of the suture, 



