ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1001 



closed ; they are proportionately large, and are connected with fine 

 pore-canaliculi in the subdermal spaces. 



The ectoderm is poorly developed ; its cells are more or less 

 polyhedral and are never flagellate. The ciliated chambers are 

 ellipsoidal or pyriform and the flagellate cells which line them are 

 closely packed. In each chamber there opens only one fine afferent 

 canaliculus which lies exactly opposite the pole at which the equally 

 delicate efferent duct is found. The whole chamber is very often 

 surrounded by a thin continuous membrane, which lies directly on 

 the basal ends of the flagellate cells ; the chambers are widely but un- 

 equally divided among the parts of the body. The mesoderm agrees 

 essentially with that of other sponges ; the connective-tissue cor- 

 puscles are extraordinarily branched, and their processes are always 

 in direct communication with one another. 



The sexes are separate ; the spermatozoa form in regular masses, 

 and like the ova are mesodermal products. Ova appear to be 

 developed at definite and constant points only. ^Reproduction may 

 also be effected by budding, and this is seen in both males and females ; 

 it is preceded by the collection of masses of amoeboid cells between 

 the subdermal cavities. 



New Monaxonid Sponge.* — Under the name of Protoleia sollasi, 

 Messrs. A. Dendy and S. O. Eidley describe a new monaxonid 

 sponge which closely agrees in many respects with the suberitid 

 Polymastix, but is distinguished by a very remarkable spicule, which, 

 both in form and position, reminds one of the characteristic " grapnel " 

 of the Tetractinellida ; there are no flesh-spicules. 



The importance of this sponge lies in its bearing on the relations 

 of the Monaxonida to the Tetractinellida, and it favours the view 

 that the latter are derived from the former ; on this point the authors 

 quote the embryological evidence which has been submitted to them 

 by Prof. Sollas. The conclusion is drawn that a tetractinellid 

 spicule is not of itself a sufficient guide as to the systematic position 

 of any sponge. 



Sponges from Port Phillip Heads.f — Mr. H. J. Carter continues 

 his account of a collection of South Australian sponges, the Calcarea 

 being still dealt with ; he finds that the facts do not justify the for- 

 mation of a distinct class for this group of sponges. 



Greensand Beds of Sponge remains.! — Dr. G. J. Hinde gives 

 an account of the beds of sponge-remains which are found in the 

 lower and upper greensands of the south of England. These beds 

 consist largely of the detached spicular remains of siliceous sponges 

 only ; in some, the silica of the spicules still retains its original 

 colloidal condition, in which it is negative to polarized light, and 

 readily soluble in caustic potash. The canals of the spicules are 

 very commonly filled with glauconite, which may also replace the 



* Aim. and Mag. Nat. Hiat., xviii. (1886) pp. 152-9 (1 pi.). 



t Ibid., pp. 126-49. J Phil. Trans., 1886, pp. 403-53 (6 pis.). 



