Sponges from South Australia. 51 



raally may be found shorter ones with lanciform ends ; minute 

 ones or mortar-spicules, both straight and sinuous, the latter 

 witli hniceolate ends, varying under 30-6000ths in. long, with 

 which the cribriform structure of the surface is more or less 

 charged ; and, lastly, large and much curved fusiform acerates 

 about 180 by 15-6000ths in., echinating the surface chiefly 

 towards the moutli; 2,. triradiates, of tlie surface generally, 

 moderately large, regular and irregular, or sagittal ; and of the 

 wall much larger, where their shafts vary under 150 by 12- 

 GOOOths, with each of the arms a little less. No. 1, respec- 

 tively, in its thin form confined to the peristome, in its minute 

 one to the surface, where, in combination with the cribriform 

 dermal sarcode, it fixes in the triradiates of this part : and the 

 stouter form chiefly to the region of the mouth, where its 

 much curved and thickened portion, wdiich is outside, is 

 directed towards this aperture, and its attenuated one sunk 

 deeply into the icall of the specimen. No. 2, triradiates, 

 to the dermal and cloacal surfaces and the wall ; in the 

 latter, their long straight shafts overlapping each other, as in 

 the foregoing species, divide the structure into horizontal inter- 

 vals, while their arms are much spread out sagitally under 

 the spicular layers of the surface and of the cloaca. Size of 

 largest group, for there are two specimens each consisting of 

 several individuals of diff"erent size agglomerated, 2-3rds in. 

 high by 1| x i in. horizontally. 



Ohs. In this species that peculiar form of the sagittal tri- 

 radiate is well developed wherein the shaft, which is, as usual, 

 straight and cylindrical, is accompanied by a vertically flat- 

 tened state of the two arms ; so that in situ, that is on the 

 lower and inner part of the ])eristome, where this form of the 

 triradiate is particularly evident, the shaft is seen to be in a 

 line with the spicules or palisading of the peristome, while 

 the flat arms are spread out sagittally across them — thus 

 acting, like the cross bar of a paling, in keeping flat and in 

 position the lower ends of the palisading. 



24. Heferopia compressa. 



Agglomerate. Specimen in form massive, compressed, 

 irregular, consisting of variously elongated conical processes 

 projecting irregularly from the general mass ; peristomed. 

 Colour white outside, sponge-brown within. Surface even, 

 consisting of cribriform sarcode, knitting together tolerably 

 large triradiates with more or less uniformity ; triradiates 

 rather elevated in the centre. Pores, the holes in the cribri- 

 form structure, averaging about 1 -900th inch in diameter, 

 among which are scattered others (? excretory) full three times 



4* 



