Ampullaceous Sac in the Spongida. 211 



turn is composed of stiff keratose, profusely ecliinated fibre, 

 densely reticulated and accompanied by the usual sarcodic or 

 soft sponge-substance, the whole traversed by the branches of 

 the excretory canal-system. Spicules of four forms, viz. : — 

 1, skeletal, acuate, smooth, slightly contracted between the 

 obtuse end and the shaft, so as give the former a slightly 

 inflated appearance, about 50 by l-6000th in. ; 2, echinating 

 spicules of two sizes, viz. one, the longest, thickly spiued 

 about the obtuse or fixed end, scantily over the shaft, and 

 smooth towards the pointed or free end, 35 by 2-6000ths in. ; 

 the other, the shortest, clavate, much spined about the fixed 

 end, which spination then ceases or is followed by a compara- 

 tively smooth interval, and then by another spined portion in 

 which the spines are vertical, after which it is smooth for 

 about a quarter of tiie length of the spicule, that is to the 

 end of the point, 19 by 2-6000ths in. exclusive of the spines, 

 which add another 6000th to the thickness ; 3, Hesh-spicule, 

 an equianchorate somewhat bent upon itself, rather obtuse at 

 the ends, {. e. not navicularly shaped, 6-6000ths in. long by 

 2^-6000ths in. across from the front arm to the back of the 

 shaft. No. 1 forms the core of the keratose fibre, whicli is 

 profusely ecliinated with both forms of no. 2, accompanied by 

 the flesh-spicule no. 3. While the fibre of the body is exclu- 

 sively that of an Echinonema, that towards the circumference 

 becomes almost as exclusively that oi 2i Psammonematous sponge 

 charged with foreign bodies and terminating in a confused 

 inflated mass at the end of each conulus. 



Hah. ? Western Port. 



Ohs. This is a remarkable sponge, for although the speci- 

 men is so small as to be insignificant in size and form, yet it 

 possesses characters which claim for it the title of a distinct 

 species, for which I propose the name above given on account 

 of the density of the echinating part of the spiculation. Here 

 there can be no doubt of the structures of two orders appear- 

 ing together in the same sponge, for the body-fibre is as 

 essentially that of an Echinonematous as the circumferential 

 or terminal part is that of a Psammonematous sponge, and 

 they are not mixed together as in the fibre of W. australi- 

 ensi's. The anchorate is less navicular in shape, that is more 

 obtuse at the ends and stouter, than that of Wilsonella austra- 

 liensi's, and the surface, instead of being smooth and over- 

 scattered with pustuliform vents, is conulated like that of a 

 Hircinia. There seems, too, to have been a great tendency 

 in its development to the formation of kerasine, for bodies as 

 large as the cells of Polyzoa that have been in its proximity, 

 and even the cells themselves of these animals, have become 



