CUBAN ANNULARIIDAE TORRE AND BAHTSCH 139 



than on the rest of the aperture; the outer peristome is marked by- 

 slender concentric lamellae. Operculum as described for the species. 



The type, U.S.N.M. No. 314957, was collected by Mrs. Reed on 

 Loma de Borje, Sierra de Cubitas Mountains, Camagiiey Province. 

 It has a little over 4 whorls and measures: Length, 13.8 mm.; greater 

 diameter, 7.9 mm.; lesser diameter, 6.5 mm. 



Bartsch also collected this species at Loma La Caridad de Mendoza 

 and Loma de Santa Cruz, near the Central Senado. 



The strong auricle and the more rounded whorls will readily dis- 

 tinguish this species from Opisthocoelicum (Opisthocoelops) excurrens 

 ([Gundlach] Pfeiffer). 



OPISTHOCOELICUM (OPISTHOCOELOPS) EXCURRENS ([Gundlach] Pfeiffer) 



Plate 9, Figure 1 



1860. Cydostoma (Tudora) excurrens [Gundlach] Pfeiffer, Malakozool. Blatter, 



vol. 7, p. 29. 



1861. Tudora excurrens Bland, Ann. Lyceum Nat. Hist. New York, vol. 7, p. 27. 

 1890. Cydostoma excurrens Crosse, Journ. Conchyl., vol. 38, p. 301. 



1920. Opisthosiphon (Opisthosiphona) excurrens Henderson and Bartsch, 

 Proc. U. S. Nat. Mus., vol. 58, p. 67. 



Shell elongate-conic, pale brown with interrupted spiral bands of 

 chestnut-brown; the elements composing these bands are arranged in 

 both axial and spiral series; interior of the aperture yellowish white, 

 conspicuously rayed by the spiral bands, which also extend faintly 

 upon the yellowish-white outer peristome of the outer lip. Nuclear 

 whorls decollated in all our specimens. Postnuclear whorls almost 

 flattened, marked by slender, somewhat retractively slanting axial 

 riblets, which are distantly spaced on the first of the remaining turns, 

 and which gradually become more closely spaced, until on the last 

 whorl they are separated by spaces which are mere impressed lines. 

 Of these riblets, 38 occur upon the first of the remaining turns, 70 upon 

 the second, 136 upon the third, and 164 upon the last. Some of the 

 riblets extend very prominently to the summit, where some become 

 fused to form tufts or hollow cusps, which are appressed to the 

 expanded basal peripheral portion of the ribs of the preceding turn; 

 some of the riblets do not become expanded, and these usually ter- 

 minate at some little distance anterior to the stronger expanded ones. 

 On the penultimate turn the axial ribs become conspicuously expanded 

 at the periphery. Suture not very strongly contracted. Periphery 

 moderately rounded. Base rather long, moderately rounded, marked 

 by the continuation of the axial ribs and by 2 strong spiral cords 

 immediately adjacent to the umbilicus, and by 3 others, a little weaker, 

 between the outer of the spiral cords and the periphery. The aperture 



