REPORT ON THE HEXACTINELLIDA. 319 



that the irregularly scattered loose parenchymal hexasters, which are present in large 

 numbers, all bear terminal rays the ends of which are knobbed or provided with small 

 thick transverse discs (PI. LXXXV. figs. 3, 5, 8, 9). The diameter of these disco- 

 hexasters varies from 0-08 to O'OS mm. The principal rays remain, as a rule, uni- 

 formly short and crowded, but the two rays of one axis are often greatly prolonged in 

 comparison with the others, and it is just in such cases that the latter usually remain 

 simple (PI. LXXXV. fig. 5), while the former become divided into two to four ter- 

 minal rays. 



4. Aphrocallistes ramosus, n. sp. (PI. LXXXVI.). 



Both among the sponges of the Challenger Expedition and among the Hexactinellida 

 dredged by Dr. Doderlein in the Sagami Bay, there are dichotomously branched round 

 tubes from 5 to 10 cm. in height, which are only from 3 to 4 mm. broad at the 

 liase, but become gradually wider in the upper branches, and finally open out by 

 cup-shaped lateral and terminal branches from 8 to 10 mm. in width. The specimen re- 

 presented from a photograph in PL LXXXVI. fig. 1, in its natural size, was obtained 

 from the Philippines (Station 210 of the Challenger Expedition, lat. 9° 26' N., long. 

 123° 45' E.), from a depth of 375 fathoms and a blue mud ground. 



The tube wall consists of the same honeycomb-like framework of six-sided meshes or 

 prismatic radial tubes, as in the cup-wall of the other species of Aphrocallistes; and 

 the microscopic examination shows that the minute structure of the meshes or prismatic 

 septa does not difi"er essentially from that abeady described. 



The tolerably smooth network of beams, which is only here and there provided with 

 delicate tubercles consists of irregularly fused hexacts, and exhibits predominantly 

 triangular narrow meshes. While the conical pegs on the dermal side run out to simple 

 points, and are directed at right angles to the bounding surface, the terminal pegs on the 

 gastral surface are elongated, provided with a rough pear-shaped end-swelling, and are 

 frec^uently obliquely directed or somewhat curved round. The conical pegs projecting 

 from the surface of the network of beams into the lumen of the radial tubes are directed 

 obliquely outwards, that is to say, towards the dermal surface. 



In the dermal skeleton, hexacts occur with a very variously developed distal ray, 

 whicb is sometimes quite fir-tree-like (PI. LXXXVI. fig. 8), sometimes club-like with 

 lateral prongs (PI. LXXXVI. fig. 4), aometimes simply rod-like or pear-shaped, or even 

 quite rudimentary and knob-like (PI. LXXXVI. fig. 3). The proximal ray equals or 

 usually exceeds the four cruciately disposed transverse rays in length. More rarely it is 

 shorter than the others, which often exhil)it an externally convex curvature (PI. 

 LXXXVI. fig. 2) Besides the dermal hexacts, numerous dermal scopulre occur. These 

 present a smooth, pointed, or terminally rounded stalk, and the outer expansion bears 



