Sponges from South Australia. 275 



should not be made the type of a new genus, in which case 

 the generic name would have to be changed. 



There is still another species among the specimens from 

 " Port Western," which may be characterized under the 

 following name : — 



Halisarca tessellata. 



In everj respect this is like the brown-coloured specimens 

 of H. australiensis from the same locality ; but the surface 

 presents a fibro-reticulated arrangement, in which the inter- 

 stices are characteristically polygonal, although variable in 

 size and number of sides. The margin (in the vertical 

 section) presents a uniform succession of translucent separated 

 spaces, which correspond with the vertically cut ends of the 

 dermal tibro-reticulation, and the ampullaceous sacs are almost 

 linear in form, that is ten times longer than they are broad. 



Besides the difference in consistence generally the dermal 

 fibro-reticulation, although like that of //. reticulata^ is not 

 accompanied by circular or elliptical interstices, as in the 

 latter, but by polygonal ones, as above stated. The succes- 

 sion of transparent spaces in the vertical section of the margin 

 is more uniform, and the ampullaceous sacs are linear, and 

 not subglobular or pyriform. 



Notwithstanding this difference in the form of the ampul- 

 laceous sacs, some of the latter, when viewed in the vertical 

 section of the other species, occasionally appear to be much 

 more narrow than the rest, hence considerably resembling the 

 form of those in H. tessellata. This, however, it should be 

 remembered may depend on the line of section, which, if 

 passing through the sho7't diameter of a compressed pyriform 

 ampullaceous sac, would give the linear form. Hence it, with 

 many more questions of a like nature, in all these species should 

 be worked out more satisfactorily, since in this necessarily hasty 

 sketch I am only able to direct attention to the existence in 

 the localities mentioned of species of the Carnosa, to which 

 it is desirable to give more extended examination. 



All the structure of Halisarca australiensis may be seen in 

 Halisarca Dujardini when the latter is fresh, only being more 

 delicate it is not so strongly marked, in short not so strongly 

 developed, in the British species ; and if H. lohularis were 

 covered with a cortical layer it would, in like manner, present 

 the same appearance, for the most remarkable part of this 

 sponge is its active ciliated surface. 



Here I might add that the species of Halisarca described 



