BRYOZOA FROM ZANZIBAR. 497 



forms from Cnrdies Creek which I considered to be malvlnensis 

 h.ive since been separated by MacGillivray as C. coiitiyua, but the 

 fossils from Bairnsdale and New Zealand are C mcdvinensis. 



The operculum of C. wasinensis is nearly semicircular with 

 large hollows fitting on to the teeth, and is similar to the 

 operculum of C gracilis. The trabeculfe (figs. 3, 4) enclose in the 

 lower part large divisions, about 7 in number, and the divisional 

 walls are yerj thick, whereas in C. gracilis var. tessellata, nov. 

 (fig. 7), they are linear with numerous divisions. 



There are about 13 tentacles. In Cellaria we find * the number 

 of tentacles is approximately the same throughout the genus, only 

 C. dennanti MacG., a species showing other difterences, has 20. 

 Now Cellaria is a well marked genus having opercula of a special 

 form, with a hollow cup fitting on to the teeth in the oral 

 aperture, and the ovicell has a characteristic chamber, and also a 

 charactei'istic ovicellular aperture. 



Le\'insen t states that a zooecium does not correspond with an 

 area, but with this I cannot agree, as I find the superficial 

 divisions appi'oximately mark off the zooecia, even though they 

 may in parts extend somewhat under the divisional line, and this 

 is the case in many geneia. 



The ovarium usually has two ova, though there may be one or 

 three, and the ovum is large when it enters the ovicell. 



Loc. Wasin,. Brit. East Africa (501) (507), 10 fath.; Ras 

 Osowamembe, 10 fath. (504); Prison Island, Zanzibar Channel 

 (505), 8 fath. 



Cellaria teniiirostris B., C. salicorniokles Aud., C. inagvifica^., 

 C. malvinensis B., C. gracilis B., have been previously described 

 from tropical regions. 



Thairopora mamillaris Lamouroux. 



Flustra mamillaris Lamouroux, " Polyp, corall. flexibles," p. 1 10 

 (1816) and add to Miss Jelly's synonyms : — 



Thairopora mamillaris MacG. Prod. Zool. Vict. dec. xx. p. 351, 

 pi. 196, fig. 2 (1890). 



Membranipora inaviillaris Hincks, Ann. Mag. Nat. Hist. ser. 6, 

 vol. viii. p. 91 (1891). 



Thidamoporella mamillaris Levinsen, Morph. & Syst. Studies 

 on Cheil. Bry. p. 194, pi. vi«. figs. 5 a-5 e (1909). 

 . There is a small piece from Chuaka, Zanzibar, which was de- 

 calcified when received. It was preserved in HgCl,, but no 

 doubt there was acid as well. The main points could, however, 

 be seen, and the opercula and mandibles were separated, and 

 although the mandibles are smaller than in the specimen received 

 from the Red Sea, to which reference is made below, yet they are 

 quite characteristic of T. mam.illaris. Levinsen has shown that 

 there are calcareous spicules in all the Thalamoporellidje, affbrding 



* Resultats du Voyage du S.Y. Belgica, " Bryozoa," p. 37 (1904). 

 t Morph. & Syst. Studies on the Cheil. Bryozoa, p. 211. 



