Sponges from South Australia. 435 



the greater abundance of sarcode in the latter (where the ova 

 are generally seen), which, when dry, assumes a sponge- 

 brown colour. These observations are premised to avoid un- 

 necessary repetition in the text, so that hereafter in the 

 descriptions the colour may not be noticed, unless differing 

 from that above mentioned. 



The " structure of the surface " or cortical portion needs no 

 remark beyond the fact that the holes of the cribrated dermal 

 sarcode, t. e. the pores, are generally much larger than in the 

 non-calcareous sponges ; then the spongozoa are nearly double 

 the size also, and in the fresh state so large that they may 

 often be seen to contain the green zoospore of an alga, which, 

 by its colour, contrasts strongly with the translucent white of 

 the spongozoon, thus favouring the view that it was taken 

 in for nourishment, just as when fed with carmine or indigo 

 paint the gummy part appears to be retained for the same 

 purpose and the colouring-matter rejected, as I have long 

 since shown (' Annals,' 1857, vol. xx. pp. 28 and 29). In 

 short, as regards this subject I know of no other means of 

 ascertaining these facts satisfactorily than by watching the 

 development of a sponge under water, that is Avhile growing, 

 which can only be done in fresh water, with the gemmule 

 or statoblast of a living SjJongiUa, as I have mentioned 

 {op. et he. cit.) ; for here there is no tearing to pieces or inter- 

 fering with the sponge, which may be transferred to the field 

 of the microscope (in the watch-glass in which it may be 

 growing) for observation, as long and as often as the student 

 thinks necessary, while a very high power (immersed of 

 course) may be brought to bear upon it during the time that 

 a solution of the carmine paint is added to the water in its 

 neighbourhood. I do not mean to state that this is the only 

 course by wdiich the sponge is nourished, for Lieberkiihn has 

 long since shown that an Infusorium may be taken in by the 

 general substance of a sponge, and there digested in a similar 

 manner to the nutritious fragments which the Infusoria them- 

 selves employ for this purpose, ex. gr. Amosba. 



The terms " cortex " and " structure of the surface " will be 

 often used synonymously ; but it should be remembered 

 that generally the surface-layer is so thin that it hardly 

 deserves this name, since it is only in one species, viz. Hypo- 

 grantia infrequens, which w^ill be hereafter described, that I 

 have found this layer so thick as to deserve the name of 

 " cortex," and of this it is impossible to get a better idea 

 than that conveyed in Polfejaetf's illustration of Ute argentea 

 {op. cit. pi. iv. fig. 3). 



Returning to our vocabulary : I have used the term " vent " 



