RIMULA. 455 



area constitute a tricarinate figure, whilst smaller ribs to tlie number of about 

 nine on each side occupy the flanks and posterior area. Extremely rich trans- 

 verse ornament pervades the entire shell. The perforation (incorrectly shown 

 in the apical figure) is at some distance from the anterior margin. 



Belations and Distribution. — Differs from B. tricarinata, Sow , in being more 

 elevated, in the less square outline of the anterior margin, and in the stronger 

 character of the side ornaments. Two specimens from the " base-bed," Lincoln. 



398. RiMUTA SUBTRICARINATA, sp. nov. Plate XLI, figs. 17 fl, 17 h. 



Descrijjtion. — This is an extremely small shell, so that even approximate 

 measurements are difficult to obtain. Fairly elevated, with the apex curved so as 

 to slightly overhang the posterior margin ; with three conspicuous anterior ribs, 

 of which the midrib is much the thickest, whilst the other two are thin and 

 divergent; these constitute a tricarinate figure with a squarish anterior margin. 

 The sides and posterior part of the shell are thickly costated, and the whole 

 surface is marked with transverse lines, so as to produce a close and delicate 

 reticulation throughout. The perforation is fairly distant from the anterior margin. 



Belations and Distribution. — While evidently related, as regards its general 

 figure, to B. tricarinata, Sow., the ornaments in this species are much closer and 

 finer, also the two divergent anterior ribs are more slender. There are five 

 specimens in my collection from the Pea-grit of Leckhampton. 



399. RiMULA ALTA, Lijcett, 1850. Plate XLI, figs. 18 a, 18 b. 



1850. EiiARGiNTJLA ALTA, Lj/ceff. Ann. Mag. Nat. Hist., 2nd ser., vol. vi, p. 416. 

 1853. — — — Proc. Cotteswold Nat. Soc, vol. i, p. 77. 



Bibliogra.phij, Sj'c. — Morris does not quote this species in his ' Catalogue ' (1854), 

 Fortunately there is one well-preserved specimen in the Jermyn Street Museum, 

 which may be accepted as the type. This is evidently a Bimida, and is so marked 

 in that collection. 

 Description : 



Length of base . . . . ■ 5*5 mm. 



Width . . . . .3-75 mm. 



Height . . . . .5 mm. 



" Shell much elevated, compressed laterally ; apex curved posteriorly, the 

 convex side beneath the apex having narrow, simple, smooth, elevated ribs, of 



