Sponges from South Australia. 197 



Fam. 1. Halisarcida. 



Halisarca australiensis^ n. sp. 



Thin and spreading, or contracted, sessile and massive. 

 Consistence soft, elastic, and tough, but yielding like dough 

 to the slightest pressure. Colour cream or pinkish yellow. 

 Surface even, smooth, covered uniformly with a meshed fibro- 

 reticulation, which contrasts strongly by its whiteness with 

 the darker colour of the interstices, but is sometimes in the 

 opposite condition, and sometimes so delicate as to be only 

 seen well under the microscope, if even then. Pores in the 

 interstices of the reticulation. Vents sparse, projecting here 

 and there. Parenchyma consisting of a fibrous reticulation 

 connected with that on the surface, which thus dips down 

 into the interior, holding together the ampul! aceous sacs 

 (Geisselkammern) ; the whole traversed by the branches of 

 the excretory canal-systems. Fibre throughout consisting of 

 delicate transparent filaments twisted together rope-like. 

 Size variable. Largest spreading specimen about 2 in. in 

 diameter by l-8th in. in its greatest thickness, thinning 

 towards the advancing circumference ; largest massive speci- 

 men, which is subglobular with crevices on the surface, about 

 3-4ths in. each way. 



Hob. Marine. Apparently extending itself over every- 

 thing with which it comes in contact. 



Log. Port Phillip Heads, South Australia. Depth 20 fath. 



Obs. As this species becomes hard by contraction in alcohol, 

 so in pure water it becomes flaccid, hence the specimens vary 

 in size a little when subjected to these conditions respectively. 

 The most striking part about it is the fibro-reticulated struc- 

 ture of the surface, which, when well developed, is very beauti- 

 ful. It appears to be particularly prone to extend itself over 

 a species of Boltenia (stalked Ascidian). 



Boltenia auslraliensis (provisional). 



There are three or more specimens of this Boltenia in the 

 collection, together with a sessile Ascidian of the common 

 stalkless form, all covered with a layer of this Halisarca, about 

 1 -24th in. in thickness; but there is only one Boltenia in 

 which the stem is perfect, and here it is 17 in. long with 

 a diameter of 7-24ths in. where it joins the head, and 

 one of l-4th in. below, where it ends in a root-like ex- 

 pansion ; while the head, which is nodosely tubercular 

 all over except towards the lower part, is 3 in. high by 

 2x| in. in its greatest dimensions; and yet the whole, from 

 top to bottom, is covered by a layer of the Halisarca. Both 



