154 Messrs. A. Dendy and S. 0. Ridley on 



stout, spinulate spicules, not vertically disposed, but for the 

 most part horizontally and irregularly, forming a compact 

 mass. Below this layer comes the general parenchyma of 

 the sponge, enclosing very numerous, scattered, spinulate 

 spicules and very well-defined stout fibres, composed of large 

 acuate or subspinulate spicules longitudinally placed, and with 

 their apices outwardly directed. These primary fibres nm 

 vertically towards the surface of the sponge ; before arriving 

 there they expand into divergent brushes of large spicules, 

 whose apices penetrate right into, or even through, the cortex. 

 Secondary skeleton-fibres, if present at all, are very ill-defined. 



(b) Of the Mammiform Processes. — The cortex and the layer 

 immediately below it are arranged very much as in the main 

 body, except with regard to the grapnel-spicules, which 

 seem to be entirely absent ; then come very definite, stout, 

 longitudinally-placed bundles of spiculo-fibre (PL V. fig. 2, «), 

 arranged mainly and fairly regularly in two concentric circles, 

 and with the spaces between them filled with a g]-eat number 

 of irregularly but closely-arranged spinulate spicules ; in the 

 centre of the inner circle of fibre-bundles is a space- almost 

 quite free from spicules and. filled with a yellow granular 

 substance. The fibres are like those of the main body. 



Slxehton-spicides. — (1) Small, slender, very slightly curved, 

 sharply and gradually pointed spinulate spicules with not 

 very well-developed oval heads (PL V. figs. 5, 5 a) ; size 

 about '157 by ■0045millim. ; these spicules occur in the outer- 

 most layer of the cortex. (2) Much larger, very stout, sharply 

 pointed, fusiform spinulates, with roundish heads ; size vari- 

 able, about "22 by '019 millim. ; in the lower cortical layer, 

 passing gradually by spicules intermediate in form and size 

 into (3) the long acuates of the fibres (PL V. fig. 3) ; these 

 are smooth, straight, fusiform, and sharply and gradually 

 pointed at the apex ; size about 1*2 by "03 millim. (4) 

 The grapnel-spicules (PL V. fig. 1,«?, and figs. 6, 6a, Qb); 

 small, long, very slender, with more or less expanded base, 

 and tapering very gradually to hair-like fineness towards the 

 apex, ending finally in a small knob provided with recurved 

 teeth. The teeth seem to be not quite constant in number} 

 commonly there are three or four, but it is extremely difficult 

 to say which, owing to the minute size of the spicule,- some- 

 times the teeth are absent, leaving only the knob (PL V. 

 fig. 6«). Length of spicule about '52 millim., thickness at 

 thickest part of shaft about '0063 millim. Oiten the axial canal 

 of the spicule is much inflated in the terminal knob, and 

 occasionally it presents traces of branches towards the teeth. 



There are no flesli-spicules of any kind. 



Locality. Simon's Bay, Cape of Good Hope, 10-20 fathoms. 



