MUSEUM OF COMPARATIVE ZOOLOGY. 271 



transverse sculpture of (on the sixth whorl twenty-six) uniform rounded riblets 

 which fail about the middle of the whorl, but appear from suture to suture 

 across the visible part of the earlier whorls; tabulated posteriorly, showing a 

 small nodule at the angle, slightly waved and oblique; lines of growth obso- 

 lete on the base but appearing as ruga? on the siphonal fasciole; spiral sculp- 

 ture of very fine rounded raised threads, uniform and continuous over the 

 whole surface; aperture simple, slightly channelled in front; outer lip rounded, 

 thin, slightly produced in the middle; inner lip reflected, nearly covering the 

 umbilical chink, polished; a few particles of light yellow fugacious epidermis 

 visible in the chink. Lon. of shell, 9.0; of aperture, 3.75; max. lat. of shell, 

 4.0 mm. 



Station 228, off St. Vincent, in 785 1ms., sand and ooze, bottom temperature 

 39°.0 F. 1 Miocene of Santo Domingo, Gabb. 



This pretty and peculiar form is named in honor of the late W. M. Gabb, to 

 whom the generic name is due. I cannot be certain without a comparison of 

 specimens whether the present shell is the same as that described by Prof. 

 Gabb, or not. But the figure is so much like our shell tht.t I can hardly doubt 

 they are very closely related, if not the same. 



Dolophanes (melanoides var.?) columbella Pall. 



Pleurotoma (Mangilia) columbella Dall, Bull. M. C. Z., IX. p. 60, 1881. 

 ? Melanopsis capula Guppy, Quart. Journ. Geol. Soc, XXII. p. 580, pi. xxvi. fig. 14, 

 1866. Gabb, St. Domingo, p. 235, 1873. 



Habitat. Station 20, 220 fms.; off Havana, Sigsbee, 158 fms. ? Upper 

 Miocene, Cumana, Guppy. 



Two specimens of this form are in the collection. Guppy's specimen, from 

 the figure, was evidently deformed. These differ from it, due allowances being 

 made for deformity, in being narrower and in the narrow shoulder in front of 

 the suture. 



The specimen originally serving as type of M. columbella is the roundest, and 

 the groove behind the siphonal fasciole is reduced to a mere chink. In the 

 Havana specimen the chink is considerably larger and the shoulder more prom- 

 inent. It seems to stand about one third of the way from D. columbella to 

 D. Gabbi. I cannot be sure, with so little material, but I suspect this gap 

 might be filled up by a graduated series of specimens if we had material 

 enough. 



Still, as the forms are not yet connected, and have already been named, it 

 seems best to leave them separate for the present. 



