CUBAN ANNUDARIIDAE TORRE AND BARTSCH 167 



MiRisiPHON, new subgenus 



Shell cylindro-conic, marked by slender, rounded, closely spaced, 

 axial ribs. Between these ribs fine microscopic axial threads are 

 present. The spiral sculpture consists of slender threads, whose 

 junctions with the axial ribs form fine nodules. Siphon a little behind 

 the peristome, directed backward into the suture. Operculum 

 typically opisthosiphonid. 



Type: Opisthosiphon (Mirisiphon) sculptum ([Gundlach] Pfeifl'er). 



OPISTHOSIPHON (MIRISIPHON) SCULPTUM ([Gundlach] Pfeiffer) 



Plate 12, Figure 8 



1857. Cyclostoma sculptum [Gundlach] Pfeiffer, Malakozool. Blatter, vol. 4, 



pp. 176-77. 



1858. Ctenopoma sculptum Pfeiffer, Monographia pneumonopomorum viventi- 



um, suppl. 1, p. 103. 

 1920. Opisthosiphon (Opisthosiphon) sculptxim Henderson and Bartsch, Proc. 

 U. S. Nat. Mus., vol. 58, p. 68. 



Shell elongate-conic, flesh colored with a yellowish tinge, marked by 

 3 broad spiral bands of brown between summit and suture, and a 

 fourth a little anterior to the periphery. Nuclear whorls decollated 

 in all our specimens. Postnuclear whorls inflated, strongly rounded, 

 marked by very regular and very regularly spaced, wavy and slightly 

 retractively slanting axial riblets, of which 34 occur upon the first, 

 44 upon the second, 76 upon the third, and 104 upon the last turn. 

 These riblets are distantly spaced on the early turns and become 

 more closely approximated as the shell increases in size; almost every 

 other one of these riblets develops into a small sharp cusp at the sum- 

 mit. The spiral sculpture consists of slender threads about equaling 

 the riblets in strength. Of these, 4 are present on the first whorl, 5 

 on the second, 10 upon the third, and 12 upon the last. They 

 render the axial sculpture slightly nodulose and slightly wavy. Suture 

 strongly constricted. Periphery inflated, strongly rounded. Base 

 short, inflated, strongly rounded, broadly, openly umbilicated, and 

 marked by the continuation of the axial riblets and by 5 spiral threads ; 

 within the umbilicus 9 additional threads are present. Aperture oval; 

 peristome double, the outer broadly expanded, of almost the same 

 width all around, adnate to the preceding turn on the parietal wall; 

 at the posterior angle it forms an auricle, which is appressed and 

 attached to the breathing siphon immediately behind it; the inner 

 peristome is slightly exserted and slightly reflected. Operculum 

 typicaUy opisthosiphonid. 



The specimen described and figm-ed, U.S.N.M. No. 493369, is one of 

 four collected at Cabo Cruz, Oriente Province. It has a little over 4 

 whorls and measures: Length, 7.3 mm.; greater diameter, 4.2 mm.; 

 lesser diameter, 3.3 mm. 



