422 UNDESCRIBED FORM OF GASTEROPOD MOLLUSK. 



apices of the foot and mantle. They become wider as they 

 extend forwards ; and at the lateral angles of the mantle 

 each divides into a notch-like furrow which separates the 

 anterior lateral part of the pedal margin from the lower 

 margin of the head-veil ; and into a deeper furrow which 

 extends across the back to become continuous with the cor- 

 responding furrow of the opposite side, and to separate the 

 mantle and head-veil from one another. 



The head presents in front and below an oval disk, 

 which consists of a number of concentric fleshy folds, in 

 contact posteriorly with the anterior marginal concavity of the 

 foot. When the margins of a longitudinal slit, winch is 

 situated in the centre of the disk, are separated by a pair of 

 needles, the dentated edges of a pair of hard dark-coloured 

 horny lateral jaws are seen and felt. The oval disk is 

 evidently the retracted condition of a short proboscis. The 

 head-veil is crescentic. Its anterior convex margin is 

 slightly fused at the middle line in front with the superior 

 margin of the oval disk ; while its posterior concave margin is 

 elevated, opaque, and separated from the front of the mantle 

 by the nuchal furrow. Its horns are directed downwards 

 and backwards, and separate the divisions of the lateral 

 grooves, as already stated. From each horn a ridge extends 

 to its anterior margin. In texture and colour the head-veil 

 resembles the mantle. 



From the bottom of the nuchal furrow in front of the con- 

 cave incision of the mantle, a semicircular fold rises so as to 

 include a transversely oval pit. The middle of the fold is 

 elevated into a lamina, which rises obliquely in front of the 

 pit. In the pit itself are two rounded papilla?, and on the 

 fore and outer part of each is a minute eye. 



At the anterior extremity and widest part of each lateral 

 groove, and immediately under each lateral angle of the 

 mantle, there is a cavity which contains branchiae. The cavity 



