388 HETEKOPHKOSYNIILE. 



of that family ; no other can receive it, and it is only by this 

 mode we have escaped from our dilemma. 



JEFFREYSIA. 



J. DIAPHANA, Alder. 



J. diaphana, Brit. Moll. hi. p. 152, pi. 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, 011 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 point 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 striae 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 



