172 MICROCERAMUS, S. G. SPIROCERAMUS. 



I have not been able to compare this form with typical 

 latus from the Pan de Guajaybon, of which the original de- 

 scription and figures are given above. 



Subgenus SPIROCERAMUS Pils. & Van., 1898. 



Proc. Acad. Nat. Sci. Phila., 1898, p. 281, type M. amplus. 



Shell thin, cylindric, composed of many narrow ivhorls; 

 spire terminating in an acute cone, the apex entire, not de- 

 ciduous. Protoconch composed of barely 2 vertically costu- 

 late whorls, several succeeding whorls subangular ; last whorl 

 rounded, without basal keel. Suture simple, not crenulate. 

 Aperture rounded, the peristome narrowly expanded, colu- 

 mellar margin dilated and free. Axis encircled by a wide, 

 compressed spiral lamella, median in each whorl. 



Eastern Cuba. The single species has the shape of Holo- 

 spira, the axis of Arangia, and the aperture and protoconch 

 of Microceramus. I regard it as a tangent from the group of 

 M. petitiana. 



21. M. AMPLUS ('Gundl.' Pfr.). PL 26, figs. 24, 29. 



Shell rimate, cylindric, with the upper third rapidly taper- 

 ing and attenuate. Corneous, very finely and very densely 

 sculptured with oblique striae, which are white except where 

 there are large, irregular corneous patches. Whorls 14-15, 

 those of the cone subangular, the later ones and last whorl 

 convex. Aperture somewhat oblique, rounded, the lip nar- 

 rowly reflexed, columellar margin dilated above, the lip-ends 

 remote. Axis encircled by a thin but rather wide spiral 

 lamella. 



Length 12, diam. 3.5 mm., whorls 15. 



Length 10.2, diam. 3.6 mm., whorls 14. 



Length 9.5, diam. 3.3 mm., whorls 14. 



Eastern Cuba: Guisa (type loc.) and San Andres, in the 

 dist. of Bayamo (Gundlach). 



Macroceramus amplus Gundl. mss., PFR., Malak. Bl., v, 

 1858, p. 44, no. 19 ; Monogr., iv, p. 689 ; vi, 351 ; Novit. Conch., 

 p. 383, pi. 89, f. 12-14. ARANGO, Fauna, p. 84. 



This peculiarly specialized form has much resemblance to 



