296 



Heterodiscobexactins (F. E. Seh.) '. seu Monodiscohexasters (Kirkp. 

 regular, the rays 75 X 6 u with scattered prickles curved centrad, disks 

 11 a in diameter with 5 sharp denticles; the axial canal extends 8,5 ii 

 from centre. Lophodiscohexasters, 8,5 /< in diameter with short smooth 

 rather thick main rays 7 // long, 2,85 a thick. The end rays 34 u long, 

 five or six in number form a circle round a central ray: the disks, very 

 extremely small, with four or five clawlike teeth. These spicules have 

 some resemblance to the lophodiscohexasters of Caidopkacus? ovi- 

 formis F. E. Sch., but the latter are much larger (114/*) and with 

 more slender main rays (7 X 1,5 /'). (\ oviformis has hexactin auto- 

 dermalia and autogastralia. A hemidiscohexaster was found, 130 /< 

 in diameter, with three single rays, and 2 main rays ending in two 

 disk-tipped end rays; one ray was broken off at the base. 



Heterohexactins ^ with tangential rays 35 ^.i long and radial rays 

 50 // long, with finely granular surface. 



Oxyhexasters are rare among Caulopliacus species where disco- 

 hexasters are greatly developed; hemioxyhexasters are found, however, 

 in C. latus F. E. Sch. 



Localities. From stations to north west of Gauss station 2450 — 

 3397 m. 



2. Rosselia antarcfica gaussi nov. subsp. 



There are ninety specimens of this subspecies, which is easily and 

 quickly recognised. The new form differs from the typical one, in 

 having calycocomes with longer, more slender and more tuberculated 

 main rays than those of the type. The main rays of calycocomes of the 

 typical form are generally smooth, rather thick, and about 13 — 16 /< 

 long, and 3,5 // thick. Those of the variety are (in specimen No. 35) 

 22 a long, 3 /< thick, and with many tubercles. In other respects, the new- 

 subspecies resembles the typical form. In specimen 4 both kinds of 

 calycocomes occur. 



The Discovery-specimen named Rossella antarctica (specimen A) 

 belongs to this subspecies. 



Locality. Gauss Station. 350 — 385 m. 



Rossella racovitxae minuta, n. subsp. 



There are 15 examples of this species. Seven specimens vary only 

 slightly from the typical form described by Top sent in the Report on 

 the Belgica Sponges p. 33: they have very large calycocomes over 300// 



1 Heterodiscobexactins (as heteroxyhexactins, lieterostauractins. lieterodiac- 

 tins etc.) F. E. Schulze names such hexactins of which the distal endrays do not 

 show the continuation (jf the axial canal, evident in the proximal ray-part. 



