MUSEUM OF COMPARATIVE ZOOLOGY. 297 



Goniis SIGAUiyrUS Lamarck. 



Sigaretus maculatus Siiy (4- *S'. zonntns Oil)., 1842, + S. rnnrtinianua Pliil., 

 184-i) and S. perspectivus Say {-^ S, depresaus Phil., 1844,-4-^'. haliotuideus 

 Reel., Orb., 11011 Linue, + S. antillarum Keel., 1851) arc the two large well 

 known species of this region. In the latter, which I have seen alive, and in 

 alcohol, a good many times, I have never been able to observe any operculum. 

 It is probable that it is generally lost at an early age. 



Sigaretus minor n. s. 



Shell small, moderately inflated, white, three or four whorled, spirally striate. 

 Nucleus small, dark brown, and glassy for one v^^horl, very finely striate spi- 

 rally and white for another whorl, when the normal adult sculpture begins 

 abruptly. Epidermis extremely thin, nearly transparent, colorless; spiral 

 sculpture alternately of a large and a small thread, separated by a distinct, 

 sharp, but very narrow groove ; on the base the threads are less crowded and 

 more uniform, but not flattened; shell perforate, little callus on the body, the 

 pillar barely reflected at its junction with the body; aperture, regarded in its 

 own plane, nearly circular. Max. alt. of shell, 4.0; max. diam. of shell, 6.0; 

 of aperture, 3.5 mm. 



Habitat. Off Sombrero, in 54 fms, ; Station 36, in 84 fms. ; U. S. Fish Com- 

 mission Station 2648, in 84 fms., mud, off Cape Florida. 



This shell differs from the two other species in sculpture. The young of 

 S. maculatus is brown, and has a much larger umbilicus and nearly smooth base, 

 with a sculpture of uniform, round, widely separated threads on a flat ground. 

 The young of S. perspectivus is flatter, has a thick epidermis, and has broad 

 flat spirals separated by broad shallow channels. 



The soft parts of S. minor have not been observed, but it is a genuine 

 Sigaretus though of small size. 



Subgenus EUNATICINA Fischer. 



Eunaticina carolinensis n. s. 



Shell naticiform, small, white, spirally striate, with an ample but not flaring 

 umbilicus; four-whorled. Nucleus brow^n at the apex, then glassy, of two 

 whorls. Remainder of the shell white, with a polished straw-colored epider- 

 mis; spire moderately elevated, suture channelled; spiral sculpture of fine 

 sharp grooves, more distant toward the periphery, about nine between the 

 periphery and suture on the last whorl; base full and rounded, rounding into 

 the umbilicus without any keel; transverse sculpture of incremental lines, 

 weaker and stronger irregularly, reticulating the earlier whorls in a faint 

 manner and crenulating finely the margin of the sutural channel; these lines 

 are fainter on the last whorl and on the periphery; aperture somewhat oblique, 



