SPONGES WHITBLEGGE. 469 



Microscleres: — palmate anisochelfe, always arranged in rosettes 

 aboutO-11 mm. in diameter; the individual chelte measure 0-05 mm. 

 in length and 0-0 15 mm. in breadth. The teeth on the upper 

 part are fairly distinct ; the lower blade, however, has its apices 

 truncated, the shaft has a clear space of about 0'015mm. in 

 length. There are a few c-like spicules about 0-15 mm. in length, 

 and abundant smaller ones which measure 0-015 mm. 



ESPERELLA MURRAY!, Ridley and Bendy. 



Esperella inurrayi, Ridley and Dend}', Chall. Rep., ZooL, xx., 

 1887, p. 67, pi. xiii., figs. 11, 13, 14, 16, 17, 18, pi. xiv., 



figs. 1-lrt. 



Station 34, 36. 



The " Thetis" collection contains six examples of this interesting 

 species obtained off Port Jackson and Botany in from 20 to 39 

 fathoms. 



Five of the specimens are pretty equal in size and measure 

 100 mm. in height and from 30 to 40 mm. in diameter. The 

 largest example is nearly 200 mm. in height and 130 mm. broad, 

 and from 25 to 40 mm. in thickness. In shape it is subflabellate, 

 with one surface concave and the other convex; the latter exhibits 

 traces of four coalescent lobes which are more marked at the 

 apical border. Judging from the appearance of the specimens, 

 it appears that the outer surface — in the living sponge — is 

 highly contractile. The surface generally presents a series of 

 scale-like plates, which evidently play an important part in the 

 inhalent currents taken in by the sponge. 



The action of these plates appears to be valvular ; each plate is 

 margined by a thin membraneous edge which, when drawn down 

 tight, effectually closes the so-called cracks or grooves. On the 

 other hand, when the plates contract, the membraneous margins 

 are elevated, and expose to view a series of fine thread-like 

 fibres, connected by a neatly perforated membraneous web. 

 Beneath this intricate trellis structure there exists a complicated 

 series of canals with numerous pores from 0*5 to 1 mm. in diameter. 

 In addition there are many larger openings from 2 to 3 mm. in 

 diameter, and 4 or 5 mm. apart. These are in keeping with the 

 size of the oscula, and I feel inclined to regard them as such, 

 rather than inhalent pores. It will thus be seen that the various 

 scale or plate-like bodies on the surface have the power by 

 contraction to close the whole of the inhalent system at will, and 

 if the larger openings are oscular in function the exhalent currents 

 are also under control by the contractility of the peculiar 

 epidermal layer. The summit of the sponge in the large specimen 

 presents about forty oscula, all of which ai'e closed by contraction 



