CUBAN ANNULAEIIDAE— TOREE AND BARTSCH 215 



Cylindrosiphona, new subgenus 



Shell siibcylindric, vnih sublamellar axial ribs, which are weakly 

 nodulose. Intercostal spaces marked by fine axial hairlines. Spiral 

 sculpture absent on spire, base, and umbihcus. Last whorl solute. 

 Operculum typically opisthosiphonid. Siphon free, beliind the peri- 

 stome at the posterior angle of the aperture. 



Type: Opisthosiphon {Cylindrosiphona) bacillum, new species. 



OPISTHOSIPHON (CYUNDROSIPHONA) BACILLUM, new species 



Shell small, subcylindric, varying in color from white through straw 

 color to brown, unicolor or banded ; peristome faintly yellow. Nuclear 

 whorls a little more than 2, inflated, strongly rounded, of almost uni- 

 form diameter, forming a truncated pupoid apex. Postnuclear whorls 

 rather high between summit and suture, moderately rounded, and 

 marked by strong lamellar axi^l ribs, which become expanded at the 

 sumjnit into rather prominent cusps. Slender, narrow, scalloplike 

 nodules are present on the ribs, which are usually best developed on 

 the early turns. The intercostal spaces are marked by microscopic 

 axial hairlines. Suture rather strongly constricted. Periphery well 

 rounded. Base short, somewhat inflated, strongly rounded, and 

 marked by the continuation of the axial ribs, which extend into the 

 umbilicus; umbilicus free of spiral sculpture. Last whorl decidedly 

 solute for about one-third of a turn. Aperture broadly oval; peri- 

 stome double, the inner slightly exserted and reflected; the outer 

 moderately expanded, a little narrower on the parietal wall than on 

 the rest of the aperture, marked by slender, concentric laminae. 

 Operculum typically opisthosiphonid. Siphon free at the posterior 

 angle of the aperture. 



The species ranges through parts of Cam.agiiey and Oriente Prov- 

 inces. 



KEY TO THE SUBSPECIES OF OPISTHOSIPHON (CYLINDROSIPHONA) BACILLUM 



Axial ribs strongly scalloped garciai 



Axial ribs not strongly scalloped bacillum 



OPISTHOSIPHON (CYLINDROSIPHONA) BACILLUM GARCIAI, new subspecies 



Plate 19, Figure 5 



This subspecies was coUected by Garcia Castaneda, near Holguin, 

 Oriente Province. It differs from typical 0. (C.) bacillum bacillum 

 in having the sculpture much more pronounced, the nodulation much 

 stronger, and the color paler. The type has 35 axial ribs on the first 

 of the remaining turns and 48 on the last whorl. 



The type, U.S.N. M. No. 535430, has 4.5 whorls remaining and 

 measures: Length, 7.6 mm.; greater diameter, 3.3 mm.; lesser diam- 

 eter, 2.8 mm. 



