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 (9), 

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

 frequently opening irregularly. Their appressed surface is 

 delicate and transparent ; their exterior rough and tuberculous, 

 and of a blackish hue. 



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

 sKt. 



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

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

 lateral edges together, to grasjD 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 Tritoniadse, 

 very near to Sci/Ucca, 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 nudibranch was dredged 

 by Mr. A. R. Hunt, near Torquay, on x\ug. 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 ^\•ould 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, 



