Fam. 1, Plate 24. 



POLYCERA LESSONII, D'Orbigny. 



P. virescens, vel luteola, corrugata, tuberculis luteis : tentaculis sub-clavatis, obtusis, 12-13 

 laminatis : velo parvo, multi-lobato : appendicibus branchiarum tubercularibus, sub ramosis luteis. 



Polycera Lessonii, D ; Orb., in Mag. de Zool. v. 7, p. 5, pi. 105. 



Polycera citrina, Alder, in Ann. Nat. Hist. v. 6, p. 340, pi. 9, f. 7-9 (young). 



Polycera modesta, Loven, Index Moll. Scand. p. 6. 



Doris illuminata, Gould, Invert. Massach. p. 4 (?). 



Hob. Common on corallines from ten to twenty fathoms water, and rarely at low-water mark, 

 Cullercoats. Dublin Bay, sparingly, J". A. 



Body about half an inch, and occasionally three quarters of an inch long, ovate oblong, 

 a little contracted behind the head; swelling in the centre., and tapering to a point posteriorly ; 

 of a yellowish-green colour, when adult, — pale lemon yellow in its younger state, — covered 

 with blunt yellow tubercles of different sizes, generally arranged in indistinct lines. The 

 skin is strongly wrinkled, and when examined with a magnifier the greenish colour is seen to 

 be chiefly communicated by a sprinkling of dark green dots on a yellowish ground. Dorsal 

 tentacles clavate, rather short, stout, and much rounded in the laminated part : laminae twelve 

 or thirteen, close and compact. Eyes very minute, scarcely visible in old individuals. Veil 

 margined with numerous tubercular points, interrupted in front, and expanded along the sides 

 of the head, forming an arch round the tentacles, behind which a line of tubercles is con- 

 tinued along each side of the back to the branchiae, where it is again expanded and produced 

 into a cluster of from two to five obtuse, ovate branchial lobes, of a bright lemon yellow : 

 behind these is a central tuberculated ridge extending to the tail. Branchiee composed of 

 three rather small, doubly pinnate plumes, of the same colour as the body, but paler. From 

 the base of the two lateral ones large branches spring, which might perhaps be considered as 

 two additional plumes. Head transversely elliptical, with the sides fleshy, and produced into 

 obtuse points. Foot pale yellowish-green, with a darker border, and a patch of reddish-brown 

 from the liver appearing through the centre ; the whole surface minutely freckled with darkish 

 green. It is squared, transversely slit, and a little produced laterally in front, behind which 

 the sides are parallel, tapering posteriorly to a bluntish point. 



The spicula are similar to those of JP. ocellata, but rather stouter in proportion to their 

 length. The heart beats sixty-two times in a minute. 



This is one of the commonest Nudibranchs from deep water on the Northumberland 

 coast, inhabiting the region of Corallines, and almost exclusively found on Gemellaria 

 loriculata, which appears to be its favorite food. This zoophyte is brought in abundantly by 

 the fishermen at Cullercoats adhering to their lines, and, by examining it carefully, individuals 



