PLEUROBRANCH^EA. 223 



Jaws tessellated as usual, the component plates short, with about 

 7 subequal denticles (figs. 93, 94). Radula with 37 rows of teeth, 

 68 to 70 lateral teeth in each half row ; teeth long and slightly 

 curved, with a shorter cusp accessory to the main one (figs. 90, 91, 

 92). This accessory cusp is lacking on the outer most teeth. 



No shell. 



Western Atlantic (Hirondelle). 



Pleurobranchillus morosus BERGH, in Resultats des Campagnes 

 Sci. Albert I, fasc. iv, p. 28, pi. 4, f. 80-93. 



K. BROCKII Bergh. Amboyna. 



This species of Pleurobranchillus is mentioned but not described 

 in Bergh's paper cited above, p. 28. 



Genus PLEUROBRANCH^EA Leue, 1813. 



Pleurobranchcea LEUE, de Pleurobranchsea novo Molluscorum 

 Oenere, Diss. Inaug., etc., Halle, 1813, title-page, and pp. 1-13, 

 plate. (Con/., p. 11 "cum animal nostrum * * * Pleuro- 

 branchcece vel Pleurobranchidii nomine insigniendum videtur."). 

 Pleurobranchcea or Pleurobranchidium of Blainville and subsequent 

 authors. Cyanogaster RUDOLPHI (where?), see Blainville, Man. de 

 Malac., p. 471. Pleurobranchcena Meckel, SWAINSON, Malacol., 

 p. 361. 



Body oblong, the united mantle and veil smaller than the foot. 

 Serrate in front and produced at the lateral angles, its edge slightly 

 overhanging on the right side, but not on the left, posteriorly, or in 

 front. Rhinophores inserted far apart, apparently on the mantle. 

 Genital apertures as in Pleurobranchus. Mouth proboscidiform. 

 Foot with a gland (more or less visible) on posterior part of sole, 

 and a spur or horn on the tail. Shell wanting. 



Radula without rachidian teeth, the laterals slender, with a single 

 long accessory denticle on the main cusp (pi. 53, fig. 84, P. meckelii 

 Blv.). 



The union of mantle and veil, widely separated rhinophores, 

 enormous size of the proboscis in dead specimens, and the lack of 

 overhanging eaves to the mantle except on the right side, render 

 this group very distinct from other Pleurobranchidce in appearance. 

 There is a posterior siphon, like that of Aplysiidce formed by folding 

 of the mantle over the rear end of the gill. 



The species are few and widely scattered. 



