4 



(often six inches long) and has the branchiae smaller : 

 it is perhaps distinct. The young of the purple 

 form has the back bordered with white, and the 

 branchiae not continuous. 



IX. Melibaea, Rang. 



Subgenus, " Doto. Ocken.''^ ? head not fur- 

 nished with a membranous veil. 

 1. fragilis, nov, sp. — Animal corpore oblongo, 

 griseo-fusco ; dorso piano ; hranchiis later- 

 alibus in seriebus sex digestis. Lon. i. 

 Lat.l. 

 Animal greyish-brown, with two filiform tentacula 

 protruding from trumpet-shaped basilar sheaths ; no 

 eyes ; six branchiae on each side, diminishing in 

 size towards the posterior extremity. Each of these 

 branchiae is subglobose in form, and composed of 

 five or six regular whorls of globules, which globules 

 are in themselves of a granular structure. These 

 branchiae are pedunculate, but not furnished with 

 sheaths at their bases, and the animal has the power 

 of casting them off when touched or otherwise irri- 

 tated. The foot is very narrow, and adapted for 

 clasping the stems of corallines. The anus and organs 

 of generation are on the right side. When put into 

 a vessel of salt water it readily creeps up the sides, 

 or up any corallines with which it may be furnished, 

 but on the least disturbance it retracts its tentaculae 

 within their sheaths, and not unfrequently drops a 

 branchus. 



On corallines in deep water at Ballaugh, not rare. 



