1902.] NUDIBRAXCnS FROM ZANZIBAR. 71 



Madrella fbrrugixosa. (Plate VI. figs. 14-16.) 



Madrellaf erriigitiea A\d. &, Hauc. Tx'ans. Zool. Soc. iii. pp. 141 2 

 (1864). 



No fi'esh details have, I believe, been published respecting this 

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

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

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

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

 margin, are ti-ansparent copper-coloui-ed cerata, into each of which 

 passes a veiy shoi't diverticulum of the liver. The black or deep 

 pui'ple ramifications of the liver ai'e visible through the doisal 

 integuments. Thei'e ai-e many more cei'ata in the large than in 

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

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

 carries several irregularly distributed tubercles or papilhp. In the 

 large specimen they pass between the iliinophoi'es and fornr a .sort 

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

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

 The lai'ge specimen had a white blotch between the iliinophores, 

 the smaller none. The form of the rhinophores is somewhat 

 unusual. They are not pei'foliate, but there is a circle of papilhe 

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

 no anterior tentacles, but the head is veiy broad and crescent- 

 shaped, with pioduced ends. The front of the foot is wide and 

 square, bvitthe corners ai'e not prominent. The mouth is ventral. 

 Both the mantle-edge and the foot ai'e wide, but between them is 

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

 The mantle overhangs the head and foiins a wide fi'ontal veil. 

 The genitid orifices are in the anterior pai't 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 Abler and Hancock. I was unable to see any 

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

 mass, but not denticulate. The radula (PI. YI. fig. 16) is triseriate 

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

 centre and aliout 7 denticulations on each side. The laterals have 

 a large spine on the outer margin 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 

 centi-al nervous system ai'e very distinct. Madrella appears to bo 

 sluggish in its movements. In confinement it discharged some 

 fluid, whicli impai-ted a ferruginous colour to the water i-ound it. 

 This discharge did not aj^pear to proceed from any particular 

 organ, but fi'Oin the whole sui-face of the body. 



The genus forms an intei'esting connecting link between the 

 Janidae and other ^olidfe. The ari-angement of the liver and 

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

 and triseriate ladula it approaches the general characters of the 

 group and departs from the exceptional peculiarities of the Janidse, 



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