164 JURASSIC BIVALVIA AND GASTROPODA 



Superfamily NATICACEA 



Family AMPULLOSPIRIDAE Cox 1930 



Genus AMPULLOSPIRA Harris 1897 



Ampullospira besairiei sp. nov. 

 PL 28, figs. 10, 11a, b, 12a, b, 13 



Specific name. After Dr. H. Besairie, collector of specimens of this species from 

 Madagascar. 



Diagnosis. Shell attaining a moderately large size for the genus (height of largest 

 specimen, from Madagascar, 52 mm.), height well in excess of diameter in undis- 

 torted specimens ; height of aperture equal to or slightly exceeding one-half of that 

 of shell. Apex acute, early whorls strongly and evenly convex, later whorls develop- 

 ing a broad, almost horizontal, slightly concave sutural shelf, separated by a rounded- 

 off angulation from the moderately convex outer face of the whorl. Last whorl 

 globose, very broadly convex at the periphery, which lies approximately along the 

 prolongation of the last suture, and with the evenly convex curve of its outline 

 continuous as far as the aperture in most specimens ; in some specimens, however, 

 the outline is even slightly concave near the aperture. Umbilical opening a narrow 

 cleft in some specimens, umbilicus perhaps absent in others. Aperture higher than 

 broad. Columellar lip concave, or else almost straight and leaning slightly to the 

 left, and forming an obtuse angle or merging in a broad curve with the parietal lip ; 

 margin of columellar lip narrowly reflected, with a slightly detached margin, partly 

 covering the umbilical cleft, and continued across the parietal region to the top of 

 the outer lip by the margin of a narrow but moderately thickened inductura. Outer 

 lip imperfect in all available specimens ; growth-lines only slightly prosocline. 



Holotype and paratypes. Holotype, no. GG.10304, ex B.P. Coll. Several 

 paratypes, including nos. GG.10305, G.65864-68, 65884-95. 



Localities and horizon. Lihimaliao creek, at a point near Mbaru creek, 

 Mandawa area, Tanganyika (type-locality) ; near site of Mandawa well no. 1, 

 Tanganyika (young specimen) ; Mont Bory, Maevatanana district, N.W. Madagas- 

 car ; S.W. of geodetic point Antery, Maevatanana district, N.W. Madagascar. All 

 probably Bajocian. 



Remarks. This species much resembles Ampullospira sharpei (Morris & Lycett) 

 (1851 : 46, pi. 11, fig. 22) from the Bathonian of England, but in that species the 

 spire is higher than in the form now described, the sutural shelf slopes slightly, is not 

 concave, and is present at an earlier stage of growth, and the last whorl is more 

 angular in outline. In the type species of Ampullospira, A. canaliculata (Morris & 

 Lycett) (1851 : 45, pi. 11, figs. 23, 23a), from the Bajocian and Bathonian of England, 

 the sutural shelf is narrower and the margin of the columellar lip scarcely reflected. 



