214 MISS I. B. J. soLLAS OX THE [June 17, 



also tlie larger, measuring 8 cm. in height and 26 cm. in circum- 

 ference, while the pink sponge is 7 cm. in height and 10 cm. in 

 circumference) the oscula agree with Topsent's description. They 

 are large — 3-6 mm. in diametei", — confined to the upper surface 

 of the sponge, and sometimes at the end of chimney-like pi-o- 

 jections which onlj^ need to fuse laterally with one anothei- in 

 order to give Topsent's dorsal crest. In the pink sponge the 

 oscula are no more than 2 mm. in diametei-, and are scattered on 

 all the free faces of the sponge and lie quite level with the geneial 

 surface. 



Both specimens seem to have incorporated in themselves any 

 foreign bodies lying on them. The canals of both are inhabited 

 by 6-rayed Ophiuroidea in various stages of fission, or rather of 

 regenei-ation following fission, one half of the disk and three arms 

 being of much smaller size than the remaining three\ 



Styles 1-0-1 '3 mm. x 0-04-0-047 mm. at their widest parts. 



Sigmata O'Ol-O-ll x 0*0055 mm., with many (10-12 were 

 measuied) intermediate sizes, difleiing in this latter particular 

 from Topsent's description. 



Trichodragmata 0'140 mm. 



Desmacella sp. 



Sponge about 15 mm. x 6 mm. 



Probablv a young specimen of D. fortls Tops. 



Styles 1-05 x 0-03 ; 0-608 x 0-005 "mm. 



Sigmata 0-016-0-089 x 0-006 mm., with a few intermediates. 



Trichodragmata 0-133 mm. 



13. OiocALYPTA MELicHLORA, n. sp. (Plate XIV, fig. 1 and 

 Plate XV. fig. 8.) 



The single specimen of this species is broken into about 20 

 pieces. It must have measured about 20 cm. in breadth and as 

 much in height, and have consisted of a massive basal part 

 breaking up distally into many flattened processes. Foi-tunately 

 two of these processes have been preserved separately and are in 

 a better condition. They show that the sponge j)ossesses the 

 structure foi-mei'ly considered to be one of the diagnostic chai'acters 

 of the genus (for Thiele's views see Abh. Senckenb. Ges. sxv. 

 1900, ID. 17) ; it has a central axis, in which the spicules run 

 longitudinally ; fi'om this arise short columns containing spicules 

 placed at right angles to the cential axis and supjDorting the 

 dermal membiane above a spacious siibdermal cavity. 



Colon 1- in spirit whitish. 



Spicules : — 



Oxeas in great vai-iety of size and form (PI. XV. fig. 8), often 

 inequiactinate, the large oxeas very broad in the middle and 

 tapering gradually to fine points. They may be bent once or 

 twice. 



1 See BatBso:), 'Materials for the Studj' of Variation,' p. 433; ai d Liitlan;, Ann. 

 & Mag. N. H. 1873, ser. 4, vol. xii. p. 323 (quoted by Bateson). 



