the Oscules of Cinachyra. 667 



F. Gilchristi has two deep depressions, poral vestibiilai- 

 and cloaca], the former having smooth walls perforated by 

 minute pores and the latter having orifices of oscules in its 

 base. 



Judging from his description and figure, Schmidt, I believe, 

 mistook the nature of tiiese depressions, describing the poral 

 as cloacal and vice versa ; for the smooth-walled deep depres- 

 sion of F. Gilchristi is undoubtedly a poral vestibule and not 

 a cloaca. Without a knowledge of the development it would 

 be difficult to say whether the openings in the floor of the 

 cloacal depression in the latter species are to be regarded as 

 an assemblage of oscules or as orifices of exhalant canals 

 opening into a cloaca terminating in one oscule ; the first 

 hypothesis seems the more probable one. 



To sum up : the depressions on the surface of the seven 

 species of Cinachyra are probably in every instance poral 

 vestibules, the oscules being separate and distinct. 



Literature. 



(i) Carter, H. J. " Report ou the .... Sponges from .... Mergui 

 Archipelago . . . ." Journ. Liun. Soc, Zool. 1887, vol. xxi. 



(2) Dendy, a. " Report on a Second Collection of Sponges from the 



Gulf of Manaar.'' Ann. & Mag. Nat. Hist. 1889, (6) iii. 



(3) Keller, C. "Die Spongienfauna des rothen Meeres. — II." 



Zeitschr. f. wiss. Zool. 1891, Bd. Iii. 



(4) KiESCHNicK, O. " Kieselschwamme von Amboina. Zool. 



Forschungsreisen Semon." Denkschr. Gesellsch. Jena, 1900, 

 Bd. v., Text, 



(5) KiRKPATRiCK, R. " Descriptions of South African Sponges. — I." 



' Marine Investigations in South Africa,' 1902. 



(6) Lendeneeld, R. von. " Spongien von Sansibar." Abhand. 



Senckenberg. Gesellsch. 1899, Bd. xxi. 



(7) . ' Das Tierreich.' Lief 19. 1903. Porifera Tetraxonia. 



(8) Schmidt, 0. 'Die Spongien des Meerbusen von Mexico.' 1879. 



(9) Sollas, W. J. " Report on the Tetractinellida collected by 



H.M.S. ' Challenger.' " Zoology, vol. xxv. 1888. 



EXPLANATION OF PLATE XIV. 



Fig. 1. Cinachyra harbata, Sollas, from the Antarctic, natural size. 



a, zone of poral vestibules ; b, zone or area of oscules. 

 Fig. 2. Vertical section through an oscule, X 5. a, oscule ; b, cortex ; 



c, main excurrent canal ; d, foraniiuiferan shell. 

 Fig. S. Cinachyra barbata h-om Kev'^nelen ('Challenger'). The surface 



pile of spicules has been rubbed oti' in the oscular region to 



show the oscules, which are here contracted to pin-points. 



a, oscules. 



