SPONGES.-HALLMANN. 



297 



glabrous, there being an entire absence of the dermal brushes 

 of spicules so characteristic of Raspailia, and, indeed, an 

 absence of any dermally situated spicules whatsoever. The 

 skeleton is a well-defined, moderately small-meshed, reticula- 

 tion of hornv fibres, and is without any trace of an "axial 

 condensation." The main or longitudinal fibres, which lie 

 i^ather wide!}" apart, are sparsely cored with long tylostyles, 

 whilst the connecting hbres are \\ ithout axial spicules ; both 

 main and connecting fibres are fairly plentifully echinated by 

 acanthostyles. 'lylostyli, exceeding in number those within 

 the fibres, occur also interstitially, disposed in approximate 

 parallelism with the main fibres ; and further, there are scat- 

 tered between the fibres, though somewhat rare in their occur- 

 rence, slender asymmetrical oxea (auxiliary spicules) which lie 

 either singly or in contiguous parallel pairs. The tylostyli, 

 which are usually more or less curved, are rarely less than 

 500 ji long, and may reach a length of i mm. ; the stoutest of 

 them have a diameter of 16 to 20 ii. The largest acantho- 

 styles measure about no x 8 ji ; and the oxea, which are 

 commonly between 270 and 320 /( in length and rarely more 

 than 4.5 pi in diameter, attain a maximum size of 410 x 5.5 ji. 



In external features the specimens are in close accord with 

 the original description. Lendenfeld's statement, however, 

 that the "sponge has the shape of a tree," is rather vague, 

 and perhaps does not convey a correct idea of its habit of 

 growth. The actual appearance of the sponge is exceedingly 

 like that of the specimen which Lendenfeld^ has figured as 

 Clathrissa arbiisciila, but which, as 1 have already ventured 

 to assert, does really represent an example of the present 

 species. 



Having examined a slide of Carter's Diciyocylindnis cac- 

 licntis,'^ presented to the Australian Museum by Prof. Dendy, 

 1 am In a position to say that this is also a species of Clathrio- 

 ilc)idi-o)i, and that it approaches fairly closely both in the size 

 and form of its spicules to C. arbuscuJa, with which it agrees 

 also in habit of growth and in having a conulose surface. The 

 maximum dimensions of the spicules prove to be as follows :— 

 Tylostyli, 975 x 16 ii; acanthostyli, 120 x 10 k; oxea, 320 x 

 3 n. The last-mentioned spicules appear to be extremely rare. 



1 Lendenfeld— ioc. cit., pl. v., fig. 2. 



2 Carter-Ann. Mag. Nat. Hist. (5), xvi., 1885, p. 354; Dendy-Proc. Roy. 



Soc Vict., via. (n.s.), 1896. p. 48. Vide also. Dendy -Rept. Pearl Oyster 

 Fisheries, Gulf of Manaar. etc.. 1905, p. 176. 



