MALAPTERA. 101 



Genus — Malaptbra, Piette. 



" Shell thin, fusiform or ovoid, wing very large, multidigitate, palmate, investing, 

 bent back, extended on the columellar side, and sometimes on the posterior portion of the 

 spire ; anterior canal placed upon an expansion which forms part of the wing, and 

 consisting of a wide furrow bent backwards as in Aporrhais." — Fischer. 



Such a genus as this possesses more resemblance to the existing Aporrhais than 

 the average Jurassic Alaria does. Indeed, Cossmann (' Stage Bathonien,' p. 71) 

 regards Malaptera as merely a subgenus of Aporrhais. Most of these shells were 

 formerly referred to Pterocera, Lamarck. 



20. Malaptera bentleyi, Morris and Lycett, 1851. Plate III, figs. 1 a, 1 b, 1 c. 



1851. Pteboceba Bentleyi, Morris and Lycett. Great Ool.-Moll., p. 15, pi. iii, 



figs. 15, 15 a. 

 1854. — — — Morris, Catalogue, p. 274. 



Cf. also Chenopus Pictaviensis, D'Orbigny. Piette, Cont. de la Pal. Fran?., 



pi. xiv, fig. 9, and pi. xix, figs. 



10 and 11. 



Bibliography , Sfc. — This is an Inferior-Oolite species described by Morris and 

 Lycett as from the Great Oolite ; but no similar form is known in the Great 

 Oolite of this country. 

 Description : 



Length of a full-sized specimen . . .32 mm. 



Ratio of width to length . . . 46 : 100. 



Spiral angle . . . .36°. 



Shell turrited, spiral angle rather convex, apex blunt. Whorls angular and 

 tumid ; posterior third of each whorl marked with very fine spiral lines, for the 

 most part scarcely visible ; the anterior two-thirds carries four strong spiral lines. 

 Body-whorl moderately large, and nearly equal to the length of the spire. It is 

 ornamented by six strong spirals, from which the digitations of the wing arise. The 

 wing embraces a very considerable portion of the spire. The posterior digitations 

 are the strongest and also the widest apart, the first one being bent upwards, so as 

 to form an angle of about 10° with the axis of the spire and nearly straight ; the 

 three anterior digitations are less strong, and project much less farther from the 

 edge of the palmated portion of the wing ; they are bent downwards in an 



