299 



The autodermalia, calycocomes, liypodermal pentactins &c., show 

 the species to be a Rossella and to be one of the „ramvitxae'-'- group. 

 Locality. Gauss Station 2. XII. 1902. 385 m. 



Rossella mixta n. sp. 



The unique specimen is oval and small being 7 mm long, 6 mm 

 broad and deep, and with a wall thickness of 1,7 mm. Diactine pleuralia 

 extend 9 mm, and pentactins forming an obscurely marked velum about 

 3 mm beyond the surface. 



Spicules. The diactine principalia are 2,5 mm. long, 11,5/^ thick, 

 with sharp-pointed roughened ends. 



The autodermal pentactins and stauractins have rays 130 u long, 

 10 /< thick at the base and 3,25 /< thick near the ends, and have the 

 surface beset with small spines (and not granular). 



The hypodermal pentactins, mostly orthotropal, have rays 1330 

 X 38 j.1, smooth or with granular surface. The auto-gastral hex- 

 actins have slender rather sharp-pointed rays 146 // long, 6 a thick at 

 the central end and 2,5 n thick at the distal end; with finely and spar- 

 sely spined surface. The calycocomes 172 /< in diameter, have main 

 rays 13 u long, 3 // thick at the central end and 3,25 /; thick distally; 

 without capitulura, with perianth-like tuft of end rays with a diameter 

 of 36 //. 



Mesodiscohexasters 87 a in diameter, with short main rays and 

 2 or 3 end rays to each main ray. 



Microdiscohexasters varying from 23 — 48 ii usually with two 

 lengths of end rays, though some of the smaller kind have only one 

 length. 



Oxyhexasters 98 /< in diameter with main rays bifurcating into two 

 slender end rays are common ; rarely stouter forms with 3 end rays to 

 each main ray are found. 



Rossella mixta belongs to a group of species (Oxydiactina group) 

 with slender sharp pointed diactine principalia. The calycocomes are 

 primitive, i. e. the end rays are attached separately to the main ray 

 and not fused into a capitulum. The auto-dermalia have spinous rather 

 than granular surface; the auto-gastralia are slender, thereby differing 

 from R. podagrosa where they are thick). 



R. htlxta seems to be the starting point of a group which branches 

 on the one hand to R. podagrosa Kirkp. and R. nuda Topsent, and on 

 the other to AidorosseUa raniioeffeni araiata n. subsp. and A. ran- 

 hoefl'em n. sp. 



Locality. The specimen came from station 8. XL 1902, 350 m. 



