458 SUMMAEY OF CUERENT BESEAKCHES RELATING TO 



The change is easy to be understood if we regard the process of 

 formation of the gemmules. By the bladder-like expansion of the 

 fold of the discoidal sponge-body, the body-wall becomes so greatly 

 extended that the spheroidal chambers opening originally into the 

 inner gastric cavity by a small canal, now by the obliteration of this 

 canal and universal expansion of its aperture assumes the hemispherical 

 form, and through the wide opening which has arisen must open 

 directly into the gastric cavity. 



Such spheroidal gemmules, which have a diameter of 2-5 mm. 

 after their separation, by means of currents never altogether absent in 

 the sea, are easily transported to another place ; and should the con- 

 ditions be favourable, even may adhere together and develope a large 

 crust. 



Sponge destructive of Oysters.* — Dr. E. v. Lendenfeld describes 

 a sponge, to which he gives the name Chalinula Goxii, which grows on 

 shells of living oysters, and disappears when these die. It is found 

 that in an oyster-bed in the Clarence river, where this sponge made 

 its appearance, the oysters were killed off. The sponge seems to 

 intercept some of the food-particles, which would otherwise be all 

 available for the oyster, which thus sooner or later gets starved ; 

 there is no direct connection between the sponge and the body of the 

 oyster. The author suggests, as a remedy, that fresh water should 

 be led through pipes to the infected locality : the oyster would not 

 thereby suffer any harm, but the sponge would be unable to live in 

 the fresh water. 



Australian Sponges.f — The fifth part of Dr. E. v. Lendenfeld's 

 monograph commences with the order Ceraospongige, which he defines 

 as " Spongiae with a skeleton composed of horny fibre. Siliceous 

 spicules produced by the sponge itself may occur in the ground- 

 substance — flesh-spicules — but never within the fibres." This order 

 is divided into two suborders, (1) MicrocamerEe, with small, spherical, 

 ciliated chambers, and (2) Macrocamerse, with large, oval, ciliated 

 chambers. Under the first suborder come the families Spongidae, 

 Aplysinidse, and Hircinidae ; in the second, are the Spongelidee and 

 Aplysillidae. 



A new subfamily of the Spongidae is formed, for forms having 

 lacunae, into which both the inhalent and exhalent apertures open. 

 In this subfamily of the Auleninae, are placed four new genera : 



(1) Holme, four species of which are very fully described and 

 figured, H. simplex, glohosa, micropora, and nidus-vesparum ; the last 

 he regards as identical with Eolopsamma laminse favosa Carter. 



(2) Aph-odite has one species, A. nardorus. (3) Aulena includes 

 A. villosa, A. nigra, and A. flahellum ; in the first species a nervous 

 system is described and figured : it consists of numerous spindle- 

 shaped cells carrying palpocils externally, whilst their deep ends 

 branch, and below them are multipolar ganglion-cells. (4) Halmopsis 

 is formed from H. australis. In the subfamily Sponginae no new 



* Proc. Linn. Soc. N. S. Wales, x. (1886) pp. 326-9. 

 t I1ji<1-. PP- 282-321 and 4S1-550 (13 j.Ih.). 



