MK. A. W. WATERS OK MEMBKANIPORIDiE. 683 



think there is no doubt tliat this last is the same as the 

 ' Challenger ' M. papillata, of which, however, the figure is some- 

 what misleading. 



The British Museum specimen in the ' Challenger ' collection 

 has the base of the opesia nearly straight and the avicularia are 

 oval. It would appear that the avicularia are sometimes pointed 

 and sometimes oval, as specimens in my collection from Tahiti 

 and from " Singapore or Philippines " have pointed avicularia, 

 whereas Hincks says that his specimen from Tahiti had oval ones. 



In my specimen just referred to, there are 2 distal rosette- 

 plates and 6 to 8 lateral ones. A specimen in the British 

 Museum from Fernando Noronha seems to be this species. 



Loc. Tahiti {S.). Station 208, ' Challenger ' (Philippine 

 Islands) ; Fernando ISToronha. 



Membeanipora umbokata, Bush. 



The specimen in the British Museum collected by the ' Chal- 

 lenger ' from Station 313 (South America), and which Busk 

 cited on page 66 of his report as M. umhonata, is Micropora 

 uncifera, B. 



The other specimen cited from St. 163 a (N.S. W.) is M. um- 

 honata. The specimen in the British Museum Catalogue col- 

 lection determined by Busk as M. imibonata is M. uncifera. 

 Although these two species have a general resemblance, they are 

 readily distinguished by examining the opesia and opercula. 



The ' Challenger ' specimen from Station 320 (S. Atlantic) is 

 about double the size of a specimen in my possession from " "W. 

 Australia," and perhaps they should be separated as varieties. 



Membrakipoea gregarta. Heller. (PI. 47. fig. 1.) 



Membranipora gregaria, Heller, '■^Bie Bryozoen des adriatischen Meeres" 

 Verliandl. der h.-h. zool.-boi. Gesellschaft, Wien, vol. xvii. 1867, p. 98, 

 pi. i. tig. 8. 



Membranipora Flemingii, var. gregaria. Waters, Ann. Sf Mag. Nat. 

 Hist. ser. 5, vol. iii. p. 122, pi. xiii. fig. 5. 



The zooecia are elongate oval, with a large triangular avicu- 

 larium between the distal end of one zooecium and the proximal 

 one of the next. The calcareous walls of the zooecia are, in the 

 Naples specimen, thin and often nearly smooth or only very 

 slightly crenulated. Heller calls the walls moderately thin and 

 granulated in the specimens from Lagosta. The mandible is not 

 curved. The ovicells are immersed, only just showing a slight 



