Fam. 1, Plate 23. 



POLYCERA OCELLATA, Alder and Hancock. 



P. viridi-nigricans, maculis magnis, tubercularibus, luteo-albidis : tentaculis elongatis, ad basin 

 tumidis, laminis 7-8 : velo parvo, multi-lobato : appendicibus brancbiarum lobato-ramosis, albidis. 



Pohjcera ocellata, Aid. and Hanc. in Ann. Nat. Hist. v. 9, p. 33. 



Triopa Nothus ? Johns, in Ann. Nat. Hist. v. 1, p. 124. 



Hab. Under stones in pools between tide-marks. Cullercoats and Whitley. Torbay. Dredged 

 in Dublin Bay. 



Body varying from three eighths to three quarters of an inch in length, linear-oblong, 

 a little contracted behind the head and tapering to a point posteriorly ; of a greenish black, 

 arising from a very dense, minute black freckling on a yellowish ground, and covered with 

 large spots of a pale yellow or reddish fawn-colour, the latter from the viscera appearing 

 through. These spots are tubercular, wide at the base and sharp pointed : they are capable 

 of extension and depression. Dorsal tentacles rather long, broad and conical at the base, 

 and smooth for about two thirds up, above which they are laminated with seven or eight, 

 sometimes nine, plates ; the apex considerably produced and truncated ; the whole is of the 

 same colour as the body, with the sides of the laminae darker, the edges and tip yellowish. 

 The eyes, which are not easily distinguished on account of the dark colour of the skin, are 

 placed a little way behind these organs. Head rounded in front, the sides of the mouth 

 fleshy, slightly produced and obtusely angular. Veil short, interrupted in front, and 

 continued round the sides of the head, with numerous yellowish white tubercular points ; 

 these are extended along the sides of the body in a tuberculated ridge, contracting towards 

 the centre of the back and expanding again near the branchiae, which they almost surround, 

 terminating on each side with a tuberculated, sub-ramose branchial lobe. Branchial plumes 

 five, rather large and imperfectly tripinnate : the three anterior plumes nearly of equal size, 

 the posterior much shorter, arising from the base of the lateral ones ; their colour is the same 

 as that of the body, but not so dark ; the margins pale and sometimes stained with fawn- 

 colour. Foot yellowish, freckled with obscure green and stained with fawn-colour in the 

 centre from the liver appearing through; truncated and rather squared in front, with the 

 sides slightly produced ; rather abruptly tapering to a point behind. 



This species very closely resembles P. Lessonii, nevertheless, after many careful ob- 

 servations of both in a living state, we feel convinced of their distinctness. The tubercles 

 are larger, fewer, and less permanent in form, but when produced they are more 

 pointed than in P. Lessonii; those that surround the dorsal area are also generally whitish, 

 while in the latter species they are of a deep yellow and more obtuse. But the principal 

 difference is in the tentacles which in P. ocellata are longer, thicker, and more conical in 

 the shaft, have fewer laminae, and are more produced at the apex than in P. Lessonii. The 

 branchial plumes too are larger and the branchial lobes more slender and less numerous. 



