HEXACTINBLLIDA. 13 



Autodermalia hexactins ; oxypentactine hypodermalia with rough or smooth 

 surface and without prickles ; oxyhexasters with extremely slender rays. 



The single specimen representing the above species is in a bad state of preserva- 

 tion, the five half-macerated fragments of grayish colour being saturated with mud. 

 Mr. Hodgson gives the information that on the return voyage the trawl was put 

 overboard and dragged for some distance over a dead level bottom of mud, but that 

 at one spot the trawl passed over a patch of stones dropped by an iceberg. This 

 would account for the condition of the specimen. With some difficulty the fragments 

 were pieced together in the manner shown on PI. III., fig. 4 ; there was no doubt 

 about the base with its small but indubitable root-tuft, nor about the oscular end, but 

 possibly a fragment may be missing from the intervening part; enough remains, 

 however, to show that the sponge was narrow at the orifice and broader at the lower 

 end than above. The specimen, as made up, is 16 cm. in length, and 5 cm. in breadth 

 below the middle. The orifice, which is 1 • 5 cm. in diameter, is partly surrounded by 

 diactin marginalia projecting about 1 • 5 cm. The root-tuft is formed of dense tufts of 

 basalia caked with mud at the ends. The velum has been mostly rubbed away ; but 

 patches of it exist, especially in the fragment bearing the oscule. The gastral 

 membrane is continuous. 



Skeleton. — The framework is formed of bundles of thin slender diactins. 



Spicules. — The principalia are diactins very long and slender, averaging 

 3500 X 1'5/x., mostly entirely smooth, and with sharp-pointed ends, though some are 

 slightly roughened at the ends. 



The autodermalia (VI. la) are hexactins, with rather sharp-pointed rays each 

 154 X 12 fi, and spined throughout; the hexactins give a pilose appearance to the 

 surface, especially when viewed under a lens. 



The hypodermalia are oxypentactins,' orthotropal, and mostly with straight 

 smooth rays, each about 900 x 20ju. ; others are larger, 1000 X 25/x, (VI. lb, b\), 

 with slightly curved wavy rays. 



The autogastralia (VI, Ic) are hexactins, considerably larger than the auto- 

 dermalia, each ray being 319/x in length, and 11 •25/i. in breadth at the base, tapering 

 to a sharp point, and only sparsely spined. 



The intermedia include holoxyhexasters (VI. Id), hemioxyhexasters (VI. Id^), 

 and only rarely monoxyhexasters (VI. Id^), about 110-125ju. in diameter ; the 

 primary rays are 8-1 O/a in length ; and the secondary rays are extremely slender. 



The calcycocomes (VI. le), 426/a in diameter, have short primary rays, 13ju. in 

 length, continuing each into a long solid capitulum 40/A'in length and 16/a in breadth, 

 whence originates a circle of eight to ten finely spined knob-tipped secondary rays. 



The holodiscohexasters (VI. If, f) of medium size, 125)u. in diameter, with 

 short primary rays dividing into four or five disk-tipped secondary rays, occur 

 only rarely. 



The microdiscohexasters (VI. Ig), 48/a in diameter, have their primary rays, 



2 I 2 



