10 
CEETACEOUS BEACIITOPODA 
a somewhat small beak -with the umhonal ridges rounded, and forming an angle 
of 110°; the termination of the beak itself is not preserved in the single 
specimen which we have. The front is divided in the middle, one-half being some- 
what bent upAvards and the other doAvnAvards, gradually, not rapidly. The surface 
is marked Avith about 10 strong, equidistant, and almost smooth radiating ribs, 
Avhieh become obsolete (or nearly so) toAvards the umbones ; they were evidently 
obtusely angular, l)ut as the sxu’face is not Avell preserved, it is difficult to say 
whether they Avcrc very sharp in the original state. 
LocaVitij. — Sirgumpore, in a Avhitc limestone. 
Formation . — Ootatoor group. 
Far. A single neural A*alve has been found in a conglomeratic limestone near 
Ootatoor. This valve belongs to a soiucaa hat more triangular, larger shell, resem- 
bling the last in general character, but having only about 12 radiating ribs, AA-hich 
are A'ery sharp and reach up to the umbo ; the ribs also arc crossed by lamelliform 
strim of groAA’th. A fragment of a limmal A^alve from tlic same locality is equally 
inflated as that of the tAqAical form from Sirgumpore ; the ribs are A’ery sharp near 
the pcrq)hery, but considerably less so towards the umbo. 
Formation . — Ootatoor group. 
Althougli there aj)pcars at the first sight to exist a great difference between the 
tAvo forms, I thinlc it highly probable that they represent only one sjiecies, and tliat 
in the typical specimen the ribs are accidentally a little Avorn doAvn. 
The species resembles inform some varieties of llhyn. dimidiata, SoAA^, but differs 
from them by its coarse ribbing. In tins point it approaches lilii/n. Beckd, Schloen- 
bach, (Xeues Jahrb. ftlr Mincralogie, &c., 1809, p. 825), being readily distinguished 
from this one, hoAvcver, by the unequal coiiA'exity of the valves. The nearest 
approach that I can find to onr fossil is the Jurassic llhyuch. pinytiis, Avhich differs 
solely by the more incurved pointed beak, and better dcA’cloiicd umbonal ridges. 
2. EnyxciioxELLA Ahrialooiiexsis, StoUezka, PI. I, Figs. 5-G. 
Fhyn. testa rotnndate snhtriyona, tumida, valca licemali attend convexiore, 
radiatim costata, cosiis 22-20, crassis, suhacutis, subteeviyatis, interstitiis mntto 
anyustiorihus separatis ; f route ohtnsata, medio tate sinnata; sinu sidjrpuadranyulari, 
moderate irrofundo, 1-5 — costato ; valca ncurali timhone pai'vo, acuto, hreriter inenrvo. 
A tumid roundly subtrigonal shell, the haemal A'alvc lieing somcAvhat more 
convex than the other ; both, hoAA'evcr, are rather abruptly truncate all round the 
margins, and arc interlocked AA'ith strong pointed teeth. The front has a broad 
almost rectangular sinus in the hmmal A'ah’c; it is 5-0 — costatc, slightly Avider than 
one-third of the total width of the shell, but not so higb as the general convexity 
of the haemal valve. The surface is ornamented with from 22-20 radiathig, strong, 
subcqual, and very closely set ribs, Avhich are slightly angidar and crossed by A’cry fine 
striae of groAvth ; all the ribs begin at the apex of each A'ah'c respectively. The 
apex of tiic neural valve is moderately prominent, pointed, and so much incurved 
