1902.] NUDIBRANCHS FROM ZANZIBAR. 71 



Madrella ferruginosa, (Plate YI. figs. 14-16.) 

 Madr^ellaferruginea MA. & Hanc. Trans. Zool. Soc. iii. pp. 141-2 

 (1864). 



No fresh details have, I believe, been published respecting this 

 genus since Alder and Hancock's description. I have seen two 

 specimens at Zanzibar, one about half an inch long and the other 

 nearly double the size. The colour of the body is a deep coppery 

 red. Round the edge of the mantle, including the anterior 

 margin, are transparent copper- coloured cerata, into each of which, 

 passes a very short diverticulum of the liver. The black or deep 

 purple ramifications of the liver are visible thi-ough the dorsal 

 integuments. There are many more cerata in the large than in 

 the smaller specimen, and it is therefore possible that they increase 

 with age. The middle of the dorsal area is bare, except that it 

 carries several irregularly distributed tubercles or papillae. In the 

 large specimen they pass between the rhinophores and form a sort 

 of rudimentary crest, but in the smaller specimen, though they 

 occur on the back, they do not pass between the rhinophores. 

 The large specimen had a white blotch between the rhinophores, 

 the smaller none. The form of the rhinophores is somewhat 

 unusual. They are not perfoliate, but there is a circle of papillae 

 round the top of the club, somewhat as in Tritonia. There are 

 no anteiioi- tentacles, but the head is very broad and crescent- 

 shaped, with pi'oduced ends. The front of the foot is wide and 

 square, but the corners are not prominent. The mouth is ventral. 

 Both the mantle-edge and the foot are wide, but between them is 

 a deep groove. In crawling the foot projects beyond the mantle. 

 The mantle overhangs the head and forms a wide frontal veil. 

 The genital orifices are in the anterior part of the right-hand side, 

 the anus in the posterior part, distinctly lateral and not dorsal. ^ 



The internal anatomy, so far as I could examine it, agreed with 

 the description of Alder and Hancock. I was unable to see any 

 salivary glands. The jaws are very large, enclosing the buccal 

 mass, but not denticulate. The radula (PL YI. fig. 1 6) is triseriate 

 and long. The median tooth has a strong blunt spine in the 

 centre and about 7 denticidations on each side. The laterals have 

 a large spine on the outer mai'gin and 8 or 9 denticulations on the 

 inner side. These denticulations seem therefore somewhat less 

 numerous than those described by A. & H. The ganglia in the 

 central nervous system are very distinct. Madrella appears to be 

 sluggish in its movements. In confinement it discharged some 

 fluid, which imparted a ferruginous colour to the water round it. 

 This discharge did not appear to proceed from any particular 

 organ, but from the whole surface of the body. 



The genus forms an interesting connecting link between the 

 Janida; and other ^olidse. The arrangement of the liver and 

 cerata connect it decisively with the former, but in its lateral anus 

 and triseriate radula it approaches the general characters of the 

 group and departs from the exceptional peculiarities of the Janidse, 



