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Prof. A. Dendy. 



Recently, while investigating and reporting upon a large collection of 

 sponges from the Indian Ocean, made by the " Sealark " Expedition under 

 the leadership of Prof. Stanley Gardiner, I have come across three more- 

 specimens containing similar spicules, and have been led to make a detailed 

 examination of these enigmatical bodies. The " Sealark " specimens belong 

 to a perfectly distinct species, but probably related not distantly to the 

 Australian sponge. I propose for the reception of the latter the new genus- 

 Collosclerophora. A diagnosis of this genus and a brief description of the- 

 type species, Collosclewphora arenacea, are given at the end of the present 

 paper. I reserve an account of the Indian Ocean sponge for my report on 

 the " Sealark " collection. 



Unfortunately the amount of material at my disposal for the investigation 

 of the jelly-spicules of Collosclerophora arenacea was extremely small. There 

 remained in my possession only a rough, unstained Canada balsam mount, 

 consisting of a single thick, hand-cut section prepared more than twenty 

 years ago. 



This preparation showed the jelly-spicules or " colloscleres," as I propose 

 to term them, with great distinctness and in very large numbers, scattered 

 through the soft tissues. They varied considerably in shape, as shown in 

 Plate 11, fig. 1, some being sausage-shaped, others boomerang- shaped, and 

 others again kidney-shaped, but always with a more or less distinct notch or 

 indentation on one side. The length of these bodies, measured in a straight 

 line from end to end, varied from about O02 to 0"03 mm. Although they had 

 perfectly sharp outlines, they were somewhat less bright in appearance than 

 ordinary microscleres, and it was at once evident that there was, apart 

 altogether from their shape, something peculiar about them. 



In order further to investigate the nature of the colloscleres it was 

 necessary to remove the section from the slide on which it was mounted. 

 This was effected by soaking in xylol, the Canada balsam being thus com- 

 pletely extracted. Part of the section was remounted in balsam, and the 

 remainder transferred to alcohol. 



After soaking in xylol the colloscleres almost completely disappeared 

 from view, so that in the fragments remounted in xylol balsam they were 

 barely recognisable, though the ordinary spicules were of course brilliant,. 

 there being a great difference in refractive index between the two. I found 

 them little, if any, more distinct in chloroform balsam, and it would appear 

 as if very prolonged soaking in balsam were necessary to render them as- 

 distinct as they were in the original preparation. They are not really 

 soluble either in xylol or chloroform. 



The original section unfortunately consisted chiefly of sand-grains, which 



