The Opistliobranchiata of South Africa. 35 



Oscanii. The back is, as in the former, continued directly into 

 the large semilunar tentacular shield ; the tentacles as well as the 

 rhinophores are thus very distant ; no shell in the flat and even back. 

 Oscaniopsis has the short form of Oscanius, and the rhachis of the 

 branchia shows as in the last a double series of nodules. They have, 

 moreover, a simple genital aperture, and the large foot shows on the 

 under side of the tail a peculiar gland. The central nervous system 

 and the elements of the mandibular plates are as in the Oscanius. 

 Sometimes the glans penis is covered with small cones. 



On the form of the tentacular shield in the Pleurobranchus 

 luniceps H. and A. Adams (in 1858) established the genus Neda ; 

 this was adopted by Gray (Guide, 1, 1857, p. 203) as well as (still 

 with some doubt) by P. Fischer (Man. de ConchyL, 1887, p. 573). 

 The genus Oscaniopsis was formed and scientifically established 

 much later. There is hardly any real reason for returning to the 

 loosely sketched denomination Neda. 



The genus has contained hitherto merely some few forms from 

 the Chinese and Indian Sea (Osc. Semperi, B. ; 0. compta, B. ; 

 0. Amboinei, Vayss."), which perhaps are not even specifically 

 different, but identical with 0. luniceps (Cuv.), which has been 

 known for a long time. 



Oscaniopsis pleurobranchzeana, B. 

 PL IV., figs. 16-21. 



One specimen was obtained off south head of Tugela Eiver by 

 shrimp-trawl from a muddy bottom at a depth of 12-14 fms. 



It had a length of the body of 3*5 cm. by a breadth of 1*8 and 

 a height of 1*2 ; the breadth of the tentacular shield was 2'2 cm., 

 the height of the rhinophores 6 mm. ; the breadth of the brim of the 

 back was, on the right side and over the tail, 8 mm. ; on the left side 

 the brim was narrower ; the gill 15 mm. long by a breadth and 

 height of 5 ; the length of the foot 3-5 cm. by a breadth at the 

 anterior end of 1-5, the length of the tail 1*2 cm. — The animal was 

 coloured white ; through the foot and the side the intestines appeared 

 brownish gray. 



The large semilunar tentacle shield gives the animal a very 

 peculiar appearance. This shield is, in the middle of the margin, 

 rather broadly notched ; it ends in tentacles in the usual way ; the 



* Vayssiere, "Monogr. de la Fam. der Pleurobranchides," 1, 1898, pi. 15, fig. 27 

 (Pleurobranchcea maculata, Q. et G.); ii., 1. I.e., 1901, pp. 15-20, i. pi. 1, 



figs. 190-204. 



