Sponges from South Australia. 287 



Pseudoceratida. 



Pseudoceratina typica, n. sp. (dry). 



Flabelllform, circular, thick, stipitate ; stem cylindrical, 

 expanding into a circular compressed head above and into 

 a root-like disk of attachment below. Consistence now, in 

 the dried state, crisp and wiry, from the hardened state of the 

 keratose fibre. Colour clear amber-brown. Surface of 

 dermal sarcode originally covered by a reticulated layer com- 

 posed of white sand, being the originally soft, fleshy, reticu- 

 lated structure charged with this material. Pores in the 

 interstices of the reticulation. Vents scattered over the surface 

 irregularly. Structure looking like that of the main fibre of 

 a Psammonematous keratose skeleton overrun by one of a 

 Lvffaria ; the latter, which is much smaller in diameter than 

 the former and represents the so-called " secondary fibre," 

 interuniting the psammoniferous branches, and present gene- 

 rally, to such a degree in the stem as to almost conceal the 

 psammonematous part of the skeleton ;* hard, cylindrical, and, 

 from desiccation, crisp now, presenting a transparent amber- 

 colour, traversed continuously and uniformly by an opaque, 

 white, homogeneous, cylindrical core, in short genuine Lujfa- 

 rid fibre. Size of specimen : — total length 9 in., of which 

 the head is b\ high by 7^x 1| in. horizontally ; stem 3^ in. 

 long by I in. in diameter in the middle, rather compressed. 



Loc. Port Western. 



Ohs. This specimen is preeminently typical of the family 

 Pseudoceratida, hence its designation. Nothing can be more 

 marked or more distinct than the two kinds of fibre of which 

 it is composed, viz. the Psammonematous and the Luffarid, 

 each being genuine of its kind. 



Before leaving the order Ceratina it may be as well to 

 allude again to the comparatively large, more or less flat, circu- 

 lar or oval, nucleated, epithelial cells, with sharply-defined cell- 

 wall, which form a layer over the soft, fleshy, iibro-reticulated, 

 dermal structure that especially characterizes the surface of 

 the Aplysime. Such cells I described and illustrated in two 

 " Pachytragous " sponges from this place in 1871 (' Annals,' 

 vol. vii. pp. 4 &c. pi. iv. figs. 6 and 14), viz. Dercitus niger 

 and Stelletfa aspera, pointing out that in the former they con- 

 stitute a " cortical layer " of several cells deep in which they 

 are held together by a soft fibro-reticulated structure or 

 " sarcodal traraa," that extends more or less into " the mouths 



