684 ME. A. W. WATEES ON MEMBRAKIPORIDiE. 



elevation below the avicularium, and are readily overlooked. No 

 spines. 



MEMBEArfipoEA cuETiEOSTEis, Hiiicks. (PL 47. fig. 2.) 



Memlaranipora curvirostris, Hmchs, Ann. §■ Mag. Nat. Sist, ser. 3, 

 vol. ix. p. 29, pi. vii. fig. 4 ; Brit. Mar. Polyzoa, p. 153, pi. xx. figs. 5, 6 ; 

 Ridley, Proc. Zool. Soc. 1881, p, 46. 



This and M. gregaria approach so closely to one another, that 

 it seemed as if gregaria must be considered as a variety, but 

 Ihe more prominent and curved avicularium of M. curvirostris 

 enables them to be separated, besides which the discovery of the 

 immersed ovicellin M. gregaria further separates them. In the 

 Naples specimen the space above the avicularium is uncovered, 

 as described by Hincks, and a rosette-plate into the avicularian 

 chamber is here visible. 



I have in one or two cases fouud a stout spine at the proximal 

 end of the zooecinm, and also there may be two oral spines, but 

 they very seldom occur in the Naples specimens, and Eidley did 

 not find any in those he examined from Brazil. 



Membeanipoea ctjetirosteis, Hindis., var. (PI. 47. fig. 12.) 



Membrauipora albida, Busk {pars), Zool. Cliall. Exp. pt. xxx. p. 63, 

 pl. XV. fig. 4. 



One of the two specimens described in the ' Challenger ' 

 Keport as alhida differs from the European M. curvirostris in 

 having smaller and less curved avicularia, but the curious un- 

 covered space above the avicularium is equally marked, and 

 except in M. permunita I am unav/are of the occurrence of these 

 spaces in any other species, and perhaps they must be considered 

 as aborted zooecia. As the specimen in the ' Challenger ' col- 

 lection at the British Museum has the avicularia less curved 

 than is shown in the figure in the Report, it is possible that 

 Busk may have had the opportunity of examining a second 

 specimen. 



My figures of this and of M. lineata(V\. 47. fig. 11), also called 

 M. albida by Busk, are prepared from sketches made when I 

 examined the specimens, and are therefore perhaps a little more 

 diagrammatic than if the specimens had been before me. 



Loc. Station 172 : Nukalofa, Tongatabu ; 18-20 fathoms, 

 coral-mud (' Challenger '). 



