388 HETEROPHROSYNID 2. 
of that family ; no other can receive it, and it is only by this 
mode we have escaped from our dilemma. 
JEFFREYSIA. 
J. prapHANA, Alder. 
J. diaphana, Brit. Moll. iii. p. 152, pl. 76. f. 1. 
Animal inhabiting a thin, glabrous, snow-white spiral shell 
of four and a half tumid volutions. Mantle pale yellow, even 
with the shell. The head is short and flat, and so deeply 
cloven as to form two distinct flake-white divergent spatulate 
lobes, with the mouth at the angle of the fissure. These 
processes have the appearance of a pair of tentacula, but the 
true ones are external to them, of hyaline flake-white, not 
very slender nor pointed, and are rather longer than the 
pseudo-tentacula. The eyes are large, black, placed very far 
back, on small, very slightly raised eminences, surrounded by 
a lucid spot or circle issuing from the skin a little within the 
internal portion of the bases of the tentacula; they are never 
exposed, but always carried on the march within the shell, 
where, from its hyaline nature, they can easily be seen. Foot 
rather long, but not slender, auricled in front, gradually 
tapering to a rounded pomt without any sort of caudal 
appendage, but with a slight longitudinal medial line on the 
under surface. The subtestaceous operculum is placed at a 
little distance from the posterior upper termination of a simple 
operculigerous lobe; it is of suboval form, pointed at one end 
and rounded at the other; it has marked subannular striz of 
increment, and is of very pale colour. We have omitted to 
mention that the operculigerous lobe extends laterally a trifle 
beyond the pedal disk, forming very narrow arcuated seg- 
ments. The whole of the foot beneath, as well as at the 
posterior end above, is pale yellow, but the upper anterior 
portion with the neck and head, from the mouth posteally, is 
marked with excessively minute, close-set, red-brown points. 
The three posterior volutions are occupied by the viscera, 
comprising an intensely dark red-brown liver, which, with the 
