42 



BRACHYPODELLA OROPOUCHENSIS, nov. sp. 

 FROM TRINIDAD, W.I. 



By GEO. C. SPENCE. 



(Read before the Society, January 8th, 1919). 



Plate I. 



Cylindrella trinitaria — Urich in " Journal of Trinidad Field 

 Naturalists' Club," no. 9 (August, 1895), vol. 2. 



Shell dextral, cylindric below, the upper third tapering to the 

 moderately wide truncation; solid but thin, darkish horn-coloured 

 and somewhat shining between the fine, regular, arcuate and wide 

 spaced whitish riblets (which are about "3 mm. apart)— the intervals 

 being five or six times the width of the riblets. "Whorls remaining 

 fourteen, the lower three or four flattened arcuate and shouldered; 

 upper whorls rather strongly convex. Suture impressed and occasion- 

 ally infringed upon by the ends of the riblets. Last whorl strongly 

 keeled below and serrated by the riblets ; these become slightly more 

 crowded on the curved descending neck which has a sulcus on the 

 outer side above the keel and which extends about half-way round the 

 body whorl. Aperture oblique, tetragonal-rounded, angular at the 

 outer and basal margins and perceptibly flattened on the outer 

 posterior side. Peristome white and broadly expanded. Axis strong, 

 sinuous and encircled by a strong smooth lamella, having a thickened 

 and rounded edge, gradually increasing from the upper whorls until 

 in the fourth from the base it reaches the greatest development and 

 then dwindles away more rapidly. Apex ? 



Length 16-5 mm.; breadth 25 mm. 



Habitat Forest on banks of Oropouche River, Trinidad. 



" The forest here is very dense and damp and right through the 

 woods are scattered upheavals of tremendous boulders of crystalline 

 limestone on which are to be found the shells Cylindrella trinitaria 

 by the hundred hanging to the dry sides of the boulders." — Urich. 



Through the kindness of Mr. Fred Taylor I recently obtained a few 

 shells collected by Mr. Urich on March 3rd, 1895, and sent by him 

 to the late Wm. Moss as C. trinitaria (Pfr.), which up to now is the 

 only Brachypodella recorded from Trinidad. The species belongs, 

 apparently, to the section Brachypodella. s. str. as defined by Pilsbry 

 in the " Manual," vol. xvi., page 64, and it is remarkable that it has 

 been overlooked or confounded for so long with B. trinitaria (Pfr.) 

 from which it varies in many points, e.g., size, contour, more widely 

 spaced riblets and axial structure. 



Figures nos. i, 2, and 3 are from photographs kindly taken by Mr. 



