RIMULA. 455 
area constitute a tricarinate figure, whilst smaller ribs to the 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. 
Relations and Distribution.—Differs from RP. 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. RiMULA SUBTRICARINATA, Sp. nov. Plate XLI, figs. 17 a, 17}. 
Description.—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. 
Relations and Distribution.—While evidently related, as regards its general 
figure, to Lt. 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. Rimuta atta, Lycett, 1850. Plate XI, figs. 18 a, 18d. 
1850. Emararnuna aura, Lycett. Ann. Mag. Nat. Hist., 2nd ser., vol. vi, p. 416. 
1853. — — -- Proc. Cotteswold Nat. Soc., vol. i, p. 77. 
Bibliography, §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 Rimula, and is so marked 
in that collection. 
Description : 
Length of base 7 : : 55 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 
