32 



crease in size and in number, and the area occupied by them extends the further 

 downwards the larger the sponge is. In the youngest specimen only the upper 

 third, in the intermediate ones the upper half, and in the oldest ones the upper 

 two-thirds, are covered with protruding lateralia. These spicules are on the 

 whole vertical to the surface, but nevertheless a great many of them, particularly 

 in the younger specimens, are directed slightly upwards. Most of the prostalia 

 lateralia arise from the apex of a small conical protuberance. They are 1-2 

 mm. apart. The lower ones are stouter and longer than the upper ones. The 

 root-tuft is aproximately cylindrical, and naked. Its thickness increases with the 

 size of the sponge and amounts in the older specimens, of the dimensions of a 

 pea, to 2-3 mm. Their length cannot be definitely stated, since all the root- 

 tufts are torn off. In one specimen the part of the root-tuft still attached to the 

 body is 3 cm. long. 



The delicate dermal reticulation has quadratic meshes. It is recognisable 

 with the naked eye, better with a magnifying glass, and can be compared to the 

 network formed by the lines of longitude and latitude on a terrestrial globe. 



The sponge is yellowish-gray, clay-coloured. This colour is proper to it 

 and not produced by silt in the sponge. 



The parenchymal macroscleres are oxyhexactines and oxydiactines. The 

 oxyhexactines are stout and have the usual form. Their rays are quite smooth 

 and gradually attenuated towards the sharp pointed end. 



The oxydiactines are straight or slightly curved, up to 1-2 mm. long and 

 10-20 f* thick. They are either quite smooth and spindle-shaped or have a well 

 defined inflation or four crosswise-arranged tubercles, the remnants of the four 

 atrophied rays, in the centre. Oxydiactines with rays about 500 /* long and 

 numerous spines are also frequent. Four spines arranged crosswise occupy the 

 centre, the others are scattered and point backwards towards the middle. The 

 whole spicule consequently appears as a true ambuncinate (pi. II, f. 13). 



The true parenchymal oxyhexactines form a regular quadratic or rather 

 cubic network, to which the quite similar hypodermal oxypentactines are ioined 

 in a regular manner. The large prostalia lateralia are oxydiactines, 3-4 cm. long 

 and over 70 i'- thick. An axial cross defining the centre is, as a rule, not dis- 

 cernable. Most of the long anchor-spicules of the basal-tuft are quite smooth. 

 It is very likely that they possess four terminal diverging and recurved trans- 

 verse rays with central canal, forming a cross, as has been described above 

 in Pheronema raphanus and also observed in some Hyalonema species. In 

 othei^s the shaft is covered throughout with stout spines, directed obliquely 

 upwards. These spines are longest in the middle. Towards the upper pointed 

 end, and also below, in the vicinity of the anchor-teeth at the distal termination 

 of the shaft, the spines become smaller. The four anchor-teeth arise from the 



