318 Mr. P. H. Gosse on a new Species of Mollusca. 



terminal one, of irregularly notched leaflets. In general,' the 

 two sides of this leaf are incurved toward each other (^), 

 facing outwards, so that the points meet and overlap loosely, 

 frequently opening irregularly. Their appressed surface is 

 delicate and transparent j their exterior rough and tuberculous, 

 and of a blackish hue. 



Head distinct ; the mouth (c) opening as a longitudinal 

 slit. 



Foot parallel- sided, nearly as wide as the body when the 

 animal is crawling on a flat ground ; but able to bring its 

 lateral edges together, to grasp such an object as a linear sea- 

 weed. It ends in an abrupt blunt point, which reaches a 

 little behind the body. 



This genus seems to find its place in the family Tritoniad^, 

 very near to Sci/Ucea, which it resembles in form, and colour, 

 and general facies ; but from which it signally differs in the 

 possession of well-formed elaborately-furnished oral tentacles, 

 and by the deeply incised, infolding branchial lobes. I have 

 not attempted to dissect my unique example ; thus my ac- 

 quaintance with its anatomy is limited to so much as can be 

 discerned from without. 



This minute, but very interesting nudibi-anch was dredged 

 by Mr. A. R. Hunt, near Torquay, on Aug. 10, 1877 ; as I have 

 more particularly described in my memoir on BelUdia Huntii^ 

 p. 315 sujyra. It was very readily kept in captivity for nearly 

 three weeks, bearing rather rough treatment with impunity ; 

 and it died at last only by an accident. It ^vould crawl rapidly 

 on sea-weeds, and occasionally would float foot upward at the 

 surface. On one occasion, as it was thus self-suspended at the 

 surface of the water, I noticed that the flotation was not per- 

 formed by the expanded foot, as I had supposed, and as is 

 usual with similar mollusks ; for the edges of the foot were 

 actually in mutual contact throughout, and thus this organ 

 was reduced to a mere line. The thought occurred, that pos- 

 sibly a narrow film of air might be inclosed within the folded 

 foot ; and I watched with interest till the animal should sink, 

 to observe whether any tiny bubble would arise from it. I 

 waited till it began to crawl on the bottom, and till I could see 

 clearly the tip of the foot projecting behind, whereby I was 

 sure that this organ was wholly flattened ; but no pellicle of 

 air appeared. 



On another occasion, when thus floating, the foot was ex- 

 panded, and the broad palms of the oral hands were in contact 

 with the circumjacent air. 



After I had kept my little captive about a week, I found 

 floating at the surface of the water a mass of spawn-ribbon^ 



