72 POLYCERIDiE. 



The gills, too, are less developed. Dr. Johnston first described 

 this variety under the name of Tergipes pidcher, which he 

 afterwards changed to Triopa claviger, recognizing it as the 

 Dons clavigera of Miiller. It is the Euplocamus plumosus of 

 Mr. Thompson, of Belfast, from the north coast of Ireland. 

 Its range extends to the Scandinavian shores. 



Genus III. THECA'CERA [*], Fleming. 



Body limaciform, smooth : mantle indistinct, occasionally 

 having a frontal veil : dorsal tentacles laminated, retractile 

 within variously formed sheaths : oral tentacles none : gills 

 plumose, non -retractile ; they surround the vent in the elevated 

 part of the back, and have lateral appendages : odontophore 

 with several lateral plates, two on each side next the centre 

 denticulated : jaws small, lateral, and coraeous. 



Thecacera differs from Polycera chiefly in having sheathed 

 tentacles; the head- veil is also less distinct or entirely wanting, 

 and the appendages less numerous. All the species are rare. 



1. Thecacera penni'gera, Montagu. 



Doris pennigera, Mont, in Linn. Trans, xi. p. 17, pi. 4. f. 5. T.pennigera, 

 A. & H. Brit. Nud. Moll. fain. 1, pi. 21 a. 



Body nearly linear, with the back elevated, and tapering to a 

 point behind, smooth, white, nearly covered with irregular bright 

 orange blotches with numerous velvety-black spots interspersed: 

 dorsal tentacles rather stout, the laminated portion yellow, with 

 black spots ; they issue from wide sheaths which are open on 

 the inner side, a little elevated in front, and rise into a blunt 

 lobe behind : head narrow, without veil : gills 3, tripinnate, 

 rather small, white, with black spots and orange blotches ; the 

 gills project from a peduncle on the centre of the back ; there 

 is a large lobate appendage on each side set considerably 

 behind the gills. L. 0-5. 



Habitat : T. pennigera appears, as far as we know at pre- 

 sent, to be confined to the south coast of England, where it 



[ * Having sheathed tentacles.] 



