62 siE CHARLES ELIOT ON [May 6, 



Maisupialia. Among the Oarnivora, Otocyon also retains the foiu- 

 molais, which Hnxley considered the primitive equipment of 

 grinders in the Canidse ^ ; and for the Insectivoi'a Oldfield Thomas 

 has recorded the existence of a fourth upper molai- in Centetes '^. 

 The occuirence of a fouith lower molar in a I'ecent Lemur 

 seemed to suggest the possibility of an ai-chaic four-molared 

 ancestor of the Primates; bvit Dr. Forsyth Major informs me 

 that, in his opinion, in the Eutheria a fourth molai- is ahvays 

 secondary. 



5, On some Nudibranchs from Zanzibar. By Sir Charles 

 Eliot, K.C.M.G., Commissioner and Consul-General in 

 the British East-African Protectorate. 

 [Received April 1, 1902.] 

 (Plates V. & YI.' and Text-figures 2-5.) 



Dui'ing the last year Mi-. Crossland has been most kindly 

 investigating for me the fauna of the eastern and westei'n coasts 

 of Zanzibai'. He has not only collected a lai-ge number of Opis- 

 thobranchs, but also greatly increased the value of his collection 

 by di-awings of the living animals. The pi'esent papei- contains 

 some of the results of his labours in the shape of notes on 

 thi'ee appai'ently new genera of Nudibranchs — Zatteria, Dunga 

 (jftColididee), and Crosslandia (Scyllaeidte), and on two interesting- 

 species on which little seems to have been written since the time 

 of Aldei" and Hancock — Melihe Jiinhriata and Madrella ferrughiosa. 

 The ^olidida? are already divided into foi'ty oi- fifty geneia, and 

 it is with reluctance that I add to their numbei-, believing that it 

 would more propeily be I'educed. But as long as the definitions 

 of the existing genera are so minute and nai'i'ow, they cannot be 

 made to accommodate fi'esh f oi'ms, for which new, though pi'obably 

 only provisional, genera must be ci'eatecl, 



Zatteria browni, gen. et sp. nov. (Plate YI. figs. 9-13.) 



Three specimens Avei-e found in seaweed collected on the I'eefs 

 round Prison Island, in Zanzibar Harbour, in May 1901. The 

 largest was "8 cm. long by "2 cm. broad. The body is long and 

 narrow, and terminates in a peculiarly slendei- tail, which is neai-ly 

 a quarter of the length of the whole animal. The cerata ai'e 

 arranged in eight transverse rows (Pl.YI. fig. 10), each row contain- 

 ing eight cei'ata, four on each side. The first two I'ows and the last 

 four are crowded togethei', but the two series in the middle ai'e 

 separated one fi'om another and from the antei'ioi- and posterior 

 clumps by considerable intei'vals. The most distinctive character 

 of the genus is the shape of the cerata (PL YI. fig. 11), which are 

 not even but swell out into two or three projecting idngs, the first 



1 P. Z. S. 1880, p. 284. 2 p. z. s. 1392^ p_ 503. 



•' For explanation of tlie Pla-tes, see p. 72. 



