MALACOZOA. GASTEROFODA. NUD1BRANCHIATA. 197 



Some of them however employ the expanded margins of 

 the mantle for swimming. 



Genus 1. Doris. 



Body oval, flat beneath, convex above, where it is 

 covered by the mantle, the margin of which projects all 

 round over the foot and mouth. Four tentacula: two 

 upper obtuse, capable of being withdrawn into a cavity ; 

 two lower or anterior very small, near the mouth, under 

 the edge of the mantle. Mouth near the anterior edge 

 of the foot, in the form of a short fleshy tube, toothless, 

 but with a denticulate lingual mass. Foot elongated, 

 oval or oblong, broader before. Branchiae in the form 

 of tufts, arranged circularly, on the superior, posterior, 

 medial part of the body, immediately before or surround- 

 ing the anal aperture. Genital organs terminating in a 

 common tubercle or papilla at the anterior third of the 

 right side, between the foot and the edge of the mantle. 



Marine, residing in clefts of rocks, under stones, or 

 on fuci, and creeping in the manner of Slugs. 



1. Doris tuberculoid, Tuberculated Doris. 



Body ovato-elliptical, convex above, and covered with 

 small, unequal, depressed, granulated tubercles ; the margin 

 of the mantle thick, somewhat undulated, projecting con- 

 siderably beyond the foot, rounded and repand anteriorly ; 

 the foot elliptical, broader before, with the margin waved ; 

 the two upper tentacula distant, mammilliform, with the 

 terminal half pinnatifido-lamellate ; the two oral tentacula 

 thick, obtuse, near the mouth, at its base ; the mouth small ; 

 the branchial tufts eight, tripinnate, circularly disposed on the 

 hind part of the body above ; the space between the edge of 

 the mantle and the foot minutely granulate, nearly smooth ; 

 the genital organs terminating in a prominent conical rugose 

 papilla, in a cavity on the right side, under the mantle-edge, 

 at the anterior third of the length of the body; the colour pale 

 leaden grey above, partly with a tinge of yellowish, and irre- 

 gularly spotted with dark-grey, as well as a few pink dots. 

 Length an inch and three-fourths, breadth nine-twelfths. 



The above description from three specimens found by Mr. 

 Alex. Murray, on the coast of Cruden, in December, 1812. 



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