232 
MOLLUSCA. CEPHALOPODA. Rotalia. 
Gen. IV. ROTALIA. — The lower disc occupied by the last 
formed whorl, the partitions of which radiate from the 
centre to the margin ; the whorls on the upper disc ex- 
posed. 
11. R. Beccaria, — Chambers nearly flat, numerous, the whorls 
dextral. 
N. spiralis, umbilicatus, geniculis insculptis, Walk. Test. Min. t. iii. f. 63. 
— N. Bee. Mont. Test. Brit. 186. t. xviii. f. 4.— On fuci and coral- 
lines. 
V olutions four or five, forming, above, a slightly convex disc ; the parti- 
tions sunk, and convex on the sides ; aperture ovate, transverse near the in- 
ner margin : the rays of the partitions of the lower disc obscure towards the 
centre. 
12. R. jB^^cmrii-perversus. — Chambers nearly flat, numerous, 
the whorls sinistral. 
N. B-p. Walk. Test. Min. t. iii. f. 6. Mmt. Test. Brit. 187. t. xviii. 
f. 6. 
This shell is found along with the last, and is said by Montagu to be 
equally plentiful. On the Scottish coast it is greatly more abundant, and 
groAvs to a superior size. 
13. R. h^ata . — Chambers tumid, few. 
Naut. inflatus, Mont. Test. Brit. Supp. 81. t. xviii. f. 3 — Among sand, 
Devonshire. 
Volutions three, the last having five ventricose articulations. The upper 
disc is more tumid, and the chambers less crowded than in either of the pre- 
ceding species. In a single specimen found on corallines, Zetland, which I 
possess, the Avhorls are sinistral, though in other respects it agrees with the 
description of Montagu. 
Gen. V. LOBATULA. — The upper disc occupied by the last 
formed whorl, the partitions of which radiate from the 
centre to .the margin ; the whorls on the lower disc ex- 
posed. 
14. L. vulgaris. — Surface of the chambers frosted ; five or 
six on the upper disc. 
N. spiralis, lobatus, anfractibus supra rotundatis subtus depressioribus. 
Walk. Test. Min. t. iii. f. 71- — Serpula lobata, Mont. Test. Brit. 515. 
— On shells and corallines, common. 
Upper disc convex, the partitions and centre slightly depressed, the cham- 
bers a little rounded. Lower disc uneven, conforming to the body on which 
it rests or adheres ; of three Avhorls ; aperture at the inner margin, trans- 
verse, and nearest the lower disc. A variety, with the whorls sinistral, oc- 
curs In nearly equal abundance. Both are subject to great variations of 
growth. 
