PLOCAMOrilORUS. 55 



Species of Polycera. 



citrina, Alder and Hanc. plebcia, Loven. 



cornuta, Abildg. pudica, "Loven. 



Lessonii, D'Orb. quadrilineata, Mull. 



rnodesta, Loven. typica, Thomp. 



ocellata, Alder and Hane. 



Genus THECACERa, Fleming. 



Body smooth. Head bilobed, with a simple frontal veil ; 

 tentacles clavate, laminated, retractile within wide open 

 sheaths. Gills pinnate, placed round the dorsal vent, sur- 

 rounded by two or more tubercular lateral appendages. 



Ex. T. pennigera, Montagu, pi. G3, fig. 1. 



The franchise in this genus are defended by lateral ap- 

 pendages, the body is smooth, and the head is bilobed. 

 There are three species, which are inhabitants of the British 

 Islauds. 



Species of Thecaccnt. 



capitata, Alder and Hanc. virescens, Alder and Hanc. 



pennigera, Mont. 



Genus PLOCAMOPHORUS, Eiippell. 



Body smooth. Tentacles clavate, without sheaths; head- 

 veil with the frontal appendages branched. Gills plumose, 

 surrounding the dorsal vent, without prominent lateral ap- 

 pendages. 



s yn. Plocamoceros, D'Orb. 



Ex. P. ocellatus, Leu chart, pi. G3, fig. 2. 



The front of the head in this genus is surrounded by 

 beautiful compound processes, and there are no elevated 



