OSCANIUB. DALY 
tentacle on each side. The gill consists of 22-24 leaflets; in front 
of it is the genital opening, forward of which lies the aperture of the 
penis, which projects, having a peculiar wing-like expansion on its 
posterior projecting part. Foot in front and at the sides at least as 
wide as the mantle, and behind it projects in a blunt angle. Ten- 
tacles slit down the outer side, cylindrical and hollow. Eyes lying 
at the base of tentacles, in the slit, so that they may be covered by 
its free edges. There is a deep incision in the back border of the 
mantle. 
Shell small, rounded, membranous and transparent, thin, simple 
and smooth, not composed of layers. 
Living animal, length 5 to 6 inches. In alcohol contracting to 
3 to 32 inches, 2 to 2} inches broad. 
Massaua W. side of the Red Sea, collected on corals in Taunaey 
(Riippell.). 
Lepus marinus ForsKAt, Icones rerum naturalium quas in Itinere 
Orientali depingi curavit Petrus Forskal, p. 9 (name only, referring 
to) plate 28, fig. A (1776).—Pleurobranchus forskalii RuPPELL & 
Leuckart, Atlas zu der Reise in N. Afrika, Neue wirbellose Thiere, 
p- 18, pl. 5. f. 2 (1828).—Pleurobranchus ruppellii IssEL, Malac. 
Mar Rosso, p. 162 (1869). Not Pleurobranchus forskahli DELLE 
CurAGE, Memoire, iii, p. 154 (November, 1828)= Oscanius tuber- 
culatus var. 
Forskal has given a characteristic illustration of this large and 
peculiar species, although in his posthumous work no description is 
given. Moreover, he uses the old pre-Linnzan formula ‘Lepus mar- 
inus” for the animal, in his explanation of plates. There is an 
objection, however, to the use of Rtippell and Leuckart’s name P. 
forskali, on account of the fact that it bears even date with Delle 
Chiaje’s similar name for another species. Under these circum- 
stances I consider that stability of the name will be best conserved 
by reverting to the earliest, rather than by adopting Issel’s proposed 
change. 
The following form is evidently nearly allied, probably identical. 
O. puRPUREUS Kelaart. Unfigured. 
Deep reddish-purple. Mantle very dark purple, and spotted with 
still darker purple. There is a bright-white zigzag line on each side 
of the back of some large specimens. Length nearly 6 inches; 4 
