REPORT ON THE HEXACTINELLIDA. 145 



short, somewhat terminally cxpauded principal rays, bear several (three, four, or more) 

 long terminals with toothed transverse terminal discs. The rosettes with slender 

 groups of S-shaped terminals, which occur abundantly in Rossella antarctica (PI. LV. 

 fig. 14), are absent in this species, and their place is taken by small plumicomes, in 

 which the short principal rays bear broad, plano-convex, transverse discs, from the 

 convex external surface of which several whorls of fine S-shaped terminals arise in 

 perianth-like fashion, as in the plumicomes of Pohjlophus 'philippinensis (PI. LIV. 

 figs. 4, 6). 



The dermal skeleton contains, besides simple medium-sized hypodermal oxypcntacts, 

 strong rough or toothed pentacts with rounded or truncated, straight, cylindrical rays, 

 such as occur in Rossella antarctica. In these forms there is a very constant occurrence 

 of a knob-like or hemispherical projection at the distal side of the point of intersection — 

 the evident rudiment of a sixth distal radial ray. 



The gastral skeleton does not differ essentially from that of Rossella antarctica. 



The long basalia, which are always smooth inside the body, but sometimes have 

 lateral barbs outside the body, bear on their extremities four markedly recurved, simply 

 pointed anchor-teeth, in which the central canal can be detected. 



Genus 4. Acanthascus, n. gen. (Pis. LVL, LVII.). 



Thick-walled goblet-shaped forms firmly attached at their base. The deep simple 

 gastral cavity opens superiorly in a round, smooth-margined osculum. From the external 

 surface of the body isolated, or more rarely grouped oxydiact pleuralia project radially. 

 The parenchyma contains oxyhexasters with short principal rays, and various disco- 

 hexasters. The dermalia are small roughened tetracts and pentacts. 



1. Acanthascus grossxdaria, u. sp. (PI. LVL). 



In the vicinity of Possession Island (Station 148, lat. 46° 47' S., long. 51° 37' E.), 

 from a depth of 210 fathoms, on a hard ground of gravel and shells, an egg-shaped 

 sponge was dredged, which in size and form resembled a large goosel^erry. The lower 

 pole had been broken ofi". At the superior pole there is a circular, smooth- margined 

 oscular aperture, leading into a saccular gastral cavity 2 '5 cm. in depth. Through the 

 smooth internal skin of the cavity the efi"erent canals can be seen, 1 to 2 mm. in width ; 

 the larger afferent canals were, in the same way, visible through the external skin. From 

 the outer surface, which is on the whole uniformly arched and smooth, numerous simple 

 smooth and pointed needles, irregularly distributed, project obliquely outwards and 

 upwards, and attain a length of 5 to 10 mm. Near the oscular opening these prostalia are 



(ZOOL, CHALL. EXP. — PART LIII. 1886.) Ggg 19 



