34 JURASSIC BIVALVIA AND GASTROPODA 



Borissiak (1905 : 12, pi. 2, figs. 10-14), the ventral margin is usually parallel with 

 the hinge-margin, although in Borissiak's " var. a " (fig. 13) there is a slight tendency 

 for them to diverge posteriorly. In the Callovian species " Cucullaea " rouilleri 

 Trautschold, referred to Macrodon by Borissiak (1905 : 8, pi. 2, figs. 1-4) and to 

 Beushausenia by Cossmann (1923 : 15, pi. 6, figs. 14-17), the two margins are as 

 strongly divergent as in the new species, but the shell is more inequilateral and dis- 

 tinctly irregular in form, some specimens having a broad, shallow sinus of the ventral 

 margin. 



Family CUCULLAEIDAE Stewart 1930 



Genus CUCULLAEA Lamarck 1801 



Cucullaea kipandeensis sp. nov. 

 PI. 3, figs, la, b 



Diagnosis. Of medium size, with the length (48-5 mm. in the holotype) well 

 exceeding the height (38 mm.), strongly inflated, most so anterior to mid-length, 

 tapering slightly in a posterior direction, with posterior half of ventral margin 

 flattened or very feebly concave. Umbonal region very broadly rounded and 

 prominent, the summit just anterior to mid-length. Posterior carina well marked 

 although rounded off, with a slight sigmoidal curvature, and delimiting a concave 

 posterior area which is just visible in the side view of the shell. Anterior two- 

 thirds of flank ornamented with strong, narrow, widely and irregularly spaced radial 

 ribs, which on its posterior third are replaced by closely spaced, weak riblets crossed 

 by concentric threads ; posterior area with a few faint radial threads. A few coarse 

 concentric corrugations mark the later growth-stages of the shell. 



Holotype and paratypes. Holotype, no. L.53146. There are two paratypes, 

 both ill-preserved. 



Locality and horizon. Kipande, W. of Tendaguru, Tanganyika ; Upper 

 Kimmeridgian, Nerinella Bed. 



Remarks. The posterior part of the hinge is not clearly exposed and it is un- 

 certain if the species is correctly included in Cucullaea. It is not so elongate as 

 typical species of Parallelodon, while its better defined posterior area and its poster- 

 ior taper distinguish it from Indogrammatodon. This species recalls a Toarcian shell 

 figured by Cossmann (1915a : 16, pi. 6, figs. 6-8) under the name Parallelodon guibali , 

 but its radial ornament is stronger than in Cossmann's shell and it is less inequi- 

 lateral. There is also a general similarity to Cucullaea elegans Roemer (1836 : 103, 

 pi. 6, figs. i6«, b), also from the Upper Lias, and it is to be suspected that Cossmann's 

 specimen should have been referred to Roemer's species. Imperfect specimens from 

 Tendaguru figured by Dietrich (1933 : 27, pi. 2, figs. 33-35) as a Cucullaea of the 

 group of C. contracta (Phillips) may have belonged to the present species, but the 

 radial ribs indicated in that author's illustrations are indistinct, perhaps owing to the 

 eroded condition of the specimens. 



