CUBAN ANNULATliroAE — TORRE AND BARTSCH 163 



KEY TO THE SUBGENERA OP OPISTHOSIPHON 



Spiral sculpture present. 



Spiral sculpture present on spire, base, and umbilicus. 

 Fine axial threads present between the heavy ribs. 



Early postnuclear whorls solute Solutapex 



Early postnuclear whorls not solute Mirisiphon 



Spiral sculpture absent on spire and base; present in umbilicus. 

 Axial ribs with individual cusps at the summit. 



Fine axial threads present between the lamellar ribs 



Bermudezsiphona 

 Fine axial|threads\bsentjbetween^thejamellar ribs 



Opisthosiphona 

 Axial ribs without individual cusps at the summit. 



Axial ribs fused to form tufts at the summit Cubitasiphona 



Spiral sculpture absent Cylindrosiphona 



SOLUTAPEX, new subgenus 



Shell ovate, with the early postnuclear whorls solute. The post- 

 nuclear whorls are marked by lamellar axial ribs and by spiral threads, 

 which form hollow tubercles at their junctions. The axial ribs also 

 become enlarged at the summit, where they form hollow cusps. The 

 spaces between the axial ribs are marked by fine, microscopic axial 

 threads. Operculum typically opisthosiphonid. 



Type: Opisthosiphon (Solutapex) caroli Agu&jo. 



KEY TO THE SPECIES OF THE SUBGENUS SOLUTAPEX 



Last whorl solute sainzi 



Last whorl adnate. 



Axial ribs closely spaced quesadai 



Axial ribs distantly spaced. 



Inner lip of outer peristome inbent in the middle echinatum 



Inner lip of outer peristome not inbent in the middle caroli 



OPISTHOSIPHON (SOLUTAPEX) SAINZI Aguayo 



Plate 11, Figure 7 



1934. Opisthosiphon sainzi Aguayo, Mem. Soc. Cubana Hist. Nat. Fehpe Poey, 

 vol. 8, p. 91, figs. 3, 4. 



Shell small, elongate-ovate, pale brown, with the axial ribs a little 

 paler. The last whorl also bears interrupted spiral bands of brown. 

 Peristome flesh colored, aperture showing the reflection of the inter- 

 rupted spiral bands within. Nuclear whorls decollated. Postnu- 

 clear whorls inflated, strongly rounded, and marked by sublamellar 

 axial ribs, which are rendered decidedly wavy and somewhat scal- 

 loped by low, broad spiral bands. Of these axial ribs 58 are present 

 on the last whorl. In addition to this sculpture, the spaces between 

 the ribs, which are about two and one-half times as wide as the ribs, 

 are marked by fine axial hairlines. Four of the low spiral cords are 



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