88 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
PLEUROLEURA GLABRA, sp. Nov. 
? = Pl. ornata, juv. (For the genus see Eliot: ‘ Nudibranchs of Southern India 
and Ceylon,” Proc. Zool. Soc. 1906, p. 676, ff.) 
The only notes are: “Khor Dongola; nudibranch; no gills. White 
with grey mottlings. Eyes halfway up rhinophores.” 
The preserved specimen is 10 mm. long and 4°3 broad. Its back is 
mottled with various shades, both light and dark, of grey and greyish green. 
A row of small black spots runs along the line of junction between the 
mantle-margin and the sides of the body, and there are others on the sides of 
the foot. 
The general shape is as usual in the genus, but the back is quite smooth 
and bears no ridges or tubercles. The rhinophores are entirely retracted into 
distinct holes about 1 mm. apart. The dorsai surface passes through them 
into the frontal shield without interruption. There is a row of pores 
(apparently cnidopores) on the mantle-edge ; most of them are set in white 
spots. 
The jaws are yellow and the edge bears several rows of longish denticles, 
which are more than a mere mosaic and become more numerous on the 
lower part of the jaws. The formula of the radula for the longest rows is 
28x 18+5+14+14+1+5+418. The central tooth has a long cusp and about 
11 distinct denticles on either side. The first lateral looks rather like half 
the central tooth and bears 7 distinct denticles on the outer side. The next 
five teeth gradually assume the ordinary hamate shape, and like the first 
lateral bear 7 denticles on the outer side. The remaining teeth vary from 16 
te 18 in number, and in the majority of rows are only 16. They are hamate 
and quite smooth, no denticles being found beyond the sixth tooth from the 
rhachis. The outermost teeth are smaller and slenderer than the rest. 
In order to preserve the single specimen the other organs were not 
examined. 
Ten species of Plewrolewra have been described, but the present specimen 
does not seem to belong to any of them. It is possible that it may be a 
young specimen of Pl. ornata, which has a tuberculate back, a broader 
radula, and more numerous denticles on the central tooth. Provisionally I 
describe it as a new species, the principal characters being the dentition and 
the smoothness of the dorsal surface. 
LOMANOTUS VERMIFORMIS, sp. nov. 
(See for the genus, Eliot : “ Notes on some British Nudibranchs,” Journ. Marine Biol. 
Assoe. vii. 1906, p. 348, ff.) 
The notes on the living animal are as follows :—‘‘ Engineer Island, Khor 
Dongola. A diver brought a large plumularian hydroid from among coral 
