Mode of Circulation in the Spongida. 119 



which is pustuliform and circumscribed on the surface, opens 

 through the sulxlermal cavities directly into a large branch of 

 the excretory canal-system, so that the particles of nutriment 

 which enter the sponge with the water must be deflected 

 afterwards by some means through the small canals (fig. 5, e) 

 which branch off from the larger excretory canal, and thus do 

 not reach their destination " direct," as above stated. 



There is evidently then a selection here, and probably 

 another when the particles arrive at the spongozoa in the 

 cavity of the ampullaceous sac, where the afferent and effe- 

 rent currents meet and where there must also be another selec- 

 tive separation, by which the excrementitious particles are 

 drafted back into the excrementary canal. I have pointed 

 out this too in Axos spintpoculum ('Annals,' 1879, vol. iii. 

 p. 287, pi. xxv. figs. 4, 5, &c.) ; but my attention lias been 

 more particularly drawn to it lately by anatomizing the struc- 

 ture of some South-Australian sponges dredged in the neigh- 

 bourhood of Port Phillip Heads in January last, which were 

 preserved in spirit through having been directly thrown into 

 the latter as they were brought up in the dredge by Mr. J. 

 Bracebridge Wilson, M.A., F.L.S., of the Church of England 

 Grammar School, Geelong, who kindly obtained and sent them 

 to me. 



This perhaps is best seen in Teichonella labyrintliica 

 ('Annals,' 1878, vol. ii. p. ,'J7, pi. ii. fig. 6 &c), wherein 

 the chambers (PI. IV. fig. 7, a-p), which are arranged in 

 juxtaposition perpendicularly to the lamina of which the 

 sponge is composed, thus pass directly through it from one 

 side to the other, having therefore on one side the pores or 

 pore-dermis (fig. 7, b), and on the other the vent (fig. 7, i) ; 

 in short exactly like those of Grantia compressa, only there 

 is no cloaca*. We must, however, regard this chamber as 

 at once ampullaceous sac and excretory canal ; for the pore- 

 dermis being at one end or side of the lamina and the vent at 

 the other, the circulation passes into the former and out at the 

 latter, through the chamber, where the nutritive particles are 

 instantly taken up by the spongozoa lining its cavity (fig. 7, h). 

 Hence the holes in -the walls of the chamber (fig. 7, g), which 

 are very numerous, may serve for the purpose of intercommu- 

 nication, where the walls of the neighbouring chambers are in 

 direct contact with each other, or for the purpose of allowing 



* I find by the spirit-preserved Teichonella labyrintliica (for there are 

 fine specimens of both T. prolifera and T. labyrintliica in Mr. Wilson's 

 collection) that in my original description of the latter (op. et he. cit.) I 

 have omitted to notice the quadriradiate spicule, which, of course, still 

 more closely allies it to Grantia compressa. 



