276 GASTEKOrODOTJS MOLLUSCA OF BER-SVICKSIIIRE. 



The sluri, whon extended, is abont three quarters of an inch loii';, of a circular 

 or oval form, the back convex, roughish or <<ranulous, of a wood-brown 

 colour, speckled with ,a few irrcojular reddish and yellow dots, duskier in 

 the centre, the marg'in of the cloak widely overlajjiiinsj the foot, deeply 

 sinnated in front, and with an obscure emartrination behind. The head is 

 truncate with two white awl-shajied tentacula, which are contractile and 

 originate in the anterior nnglcs, having the eyes, which are black and very 

 distinct, at their external bases. The mouth i>! terminal, furnished within 

 the fleshy lip with small cartilaginous jaws, and a long, narrow, linear, or 

 riband-shaped tongue, rougliened with spinules arranged in regular series. 

 Above the head, and under the cloak, there is a large slit which leads to 

 the branchial cavity and the water of respiration is conducted to this wide 

 orifice by a short canal formed bj- a fold of the cloak ; and it is this fold 

 which produces the frontal sinuation, for there is really no interruption 

 in the margin of the cloak. Within the cavity there lies retroHected the 

 male organ of generation, which seems very large in proportion to the 

 animal : it is somewhat compressed, obtuse, with a long point directed 

 backwards. Foot oblong, truncate in front, where it is opaque milk-white, 

 the rest of it being watery white. The space between it and the cloak is 

 more or less tinted with black or violet. 



The shell is concealed and embedded in the cloak, occupying a dorsal and 

 central position. It is three linos broad and about five long, ear-shaped, 

 convex, milk-white, even and apparently smooth ; but, vehen looked at 

 through the magnifier, it is seen to be wrinkled by the lines of growth ; 

 spire depressed, small, consisting of a single whorl ; aperture very patulous, 

 oblong, the inferior margin somewhat truncate, the pillar lip flattened, and 

 continued in a spiral form within the shell. 



The creature creeps very slowly, and, when in progression, raises itself on the 

 foot, while, at the same time, the tentacula are extended to the utmost, 

 and protrude beyond the margin of the cloak : when at rest, they are kept 

 concealed under this their penthouse. It swims easily in a reversed 

 position at the surface, the foot being then made slightly concave. The 

 form of the foot is variable ; for sometimes the animal will expand it until 

 it becomes almost circular, or extend it until it forms an oblong square 

 obtusely pointed behind. When alarmed, the body is contracted so that 

 the edges of the cloak meet together on the ventral aspect, and the foot is 

 greatly narrowed. The eyes are proportionably large, and are visible from 

 below, shining through the transparent skin. 



