184 EEPORT ON THE NUDIBRANCHIATE 



brouglit up in the trawl. A specimen was taken in April, 1888, 

 forty miles nortli of the Longships lighthouse. Early in May of 

 this year a mass of Molluscan spawn was brought to us by a trawler 

 which I think must have been deposited by one of these fine Nudi- 

 branchs. It was in the form of an exceedingly long and narrow 

 ribbon, greatly convoluted, and was of a salmon-pink colour as 

 nearly as I can remember. I unfortunately did not appreciate its 

 importance at the time and took no notes of it, but I am now 

 almost sure that it must have been the spawn of this Tritonia. On 

 August 25th, 1887, Cunningham dredged a young specimen an inch 

 and a quarter long, in nineteen fathoms' water, one mile south of 

 the Mewstone. 



19. T. PLEBEiA, Johnston. 



This species is taken somewhat frequently. In September of 

 last year I found two specimens in a piece of rock bored by Saxicava, 

 one of them being only half an inch in length. This stone had 

 been brought up with the dredge from south of the Mewstone, and 

 other captures show the species to be fairly common there. One 

 obtained on May 21st showed somewhat peculiar characters. The 

 colour was entirely salmon-pink, deeper on the back from the colour 

 of the liver appearing through the integument. The oral veil was 

 entire, semicircular, and not produced into tentacular prominences, 

 hut with a tendency to form four obtuse angles, two on each side. 

 There were five pairs of branchiae (the anterior pair much the 

 largest) and no small intermediate ones. The edges of the tenta- 

 cular sheaths were entire, but not so regular as in Hancock's figures 

 in the Monograph. Around each of the branchi^ and around the 

 tentacular sheaths was an area of white pigment, opaque. Length, 

 just over half an inch. 



This species is also occasionally obtained inside the Sound. One 

 specimen was taken from the Cattewater on November 20th, 1888, 

 and on the next day another was obtained from east of the Mallard 

 Buoy. These, however, had probably been thrown overboard with 

 the rest of the '^scruff" from trawlers on their way to Sutton Pool. 

 They were probably at the time fixed to pieces of Alcyonium digi- 

 tatum upon which they feed, and in relation to which, as Giard has 

 pointed out, their colour and form are evidently serviceable as 

 affording a protective resemblance to their surroundings. On the 

 day of its capture the individual from the Cattewater spawned on a 

 frond of Fucus serratus in a dish ; the coil had six perfectly regular 

 turns, attached at short intervals to the weed. The specimen from 

 the Mallard had only four tentacular prominences on the oral veil ; 



