REPORT ON THE HEXACTINELLIDA. 91 



fact, intersections with and without such a cross alternate quite regularly both in the 

 longitudinal and transverse direction. 



The parenchyma is richly provided with oxyhexasters, each of the principal rays of 

 which bears four or three straight diverging terminals (PI. XVII. fig. 8). Here and there 

 I also found an oxyhexaster form with much curved terminal rays (PI. XVII. fig. 7), 

 though it remains doubtful whether this type really belongs to the sponge. On the other 

 hand, more frequently, and undoubtedly belonging to the sponge, characteristic hexact 

 spicules occur which, like those of Holascus polejaevii represented in PI. XVII. fig. 4, 

 bear on each of the strong principal rays (which are widened and petaloid towards the 

 exterior) a bundle of eight or more markedly diverging terminals. The terminal expansion 

 of the principal rays is even larger, and more sharply separated from the inner portion 

 than in the above-mentioned species. 



The hypodermalia resemble those of Holascus polejaevii, and are, like the latter, 

 extended outwards by the longer apposed, thin, pointed diacts. 



The hypogastraha on the other hand are not pentacts but slender hexacts, in which 

 the somewhat swollen proximal ray, projecting freely inwards into the gastral cavity, is 

 beset with small prongs. 



Genus 2. Malacosaccus, n. gen. (Pis. XVIII., XIX.). 



These sponges are saccular or tubular forms, with a flabby readily pliable wall, 

 whose outer surface appears uniformly even, while on the inner surface numerous, 

 larger or smaller, round openings of the efi"erent passages occur in irregular distribution. 

 The inferior extremity has not been observed, but the superior exhibits a wide opening 

 surrounded by a narrow smooth margin. 



The principalia are represented by hexacts with long, thin, flexible rays, which are 

 disposed in radial, longitudinal, and transverse directions, becoming apposed to one 

 another, and partly interwoven to form a cubical lattice-work. Oxyhexasters and disco- 

 hexasters also occur in the parenchyma. 



On the projecting rays of the sword-shaped hexact hypodermalia and hypogastralia, 

 floricomes occur. The epidermal floricomes are larger and stronger than the epigastral. 



1. Malacosaccus vastus, n. sp. (PI. XVIIL). 



In the south of the Indian Ocean, at a locality about halfway between the Cape of 

 Good Hope and Kerguelen (Station 146, lat. 46" 46' S., long. 45° 31' E.), there was 

 trawled, from a depth of 1375 fathoms, and from a bottom of Globigerina ooze, a flabby 

 plate which could be folded like a woollen cloth. Some fragments belonging to the 



