HEXACTINELLIDS WITH DISCOCTASTERS. 



55 



above-mentioned pentactins are supplemented by sbort smooth diactias 

 with or without annular swelling at centre. 



Au togas tralia are almost exclusively rough hexactins of approxi- 

 mately same dimensions as autodermalia. They are never present in 

 sufficient numbers as to form a continuous lattice-work. The gastral 

 layer therefore possesses gaps of small but variable size, bounded by 

 beams consisting of hypogastral diactins, intermedial rosettes and auto- 

 gastralia, similarly as in Acanthascus cactus. 



(i. Staurocalyptus Roeperi (F. E. Sch.) 



This species is based on two specimens obtained by " Challenger " to 

 the south of Puerta Bueno in Patagonia. It is not represented in Saga- 

 mi Sea and is directly known to me only through two slide-preparations 

 kindly sent to me by Prof. Schulze. 



The body should be sac-like or cup-like with sharp, smooth oscular 

 edge. The subdermal space, as seen through the even lattice-work of 

 the dermal membrane, should form irregularly scattered, elongated, an- 

 gular or spindle-shaped pits, whence arise rather narrow afferent canals. 

 On the inner surface round sharply contoured depressions of various 

 sizes occur, into the bottom of which the more or less wide efferent 

 canals open. 



Spiculation closely similar to that of foregoing species ; but differing 

 in having much more slender rays to intermedial rosettes, dermalia and 

 gastralia ; in the sparing quantity of prickles on dermalia and gastralia ; 

 etc. 



Discoctasters with radius of 05-83,«, without appreciable difference 

 in size according to position. Principals slender, not exceeding Afi in 

 breadth ; with 2-5 nearly straight, slightly diverging terminals with 

 minute, piu-bead like discs. 



Oxyhexasters very slender rayed ; 44-65/z in radius, those near the 

 dermal surface being in general slightly smaller than those more deeply 

 situated. Principals short, often exceedingly short, bearing 2-3 straight 

 or wavy, obsoletely rough terminals. Cases of uniterminal principals 



