52 



I. MIMA. 



31. A. mitsukurii, n. sp. 



Autodermalia, stauractins with occasional pentactins ; rays stout, strongly 

 spiny, 110 — 170 fi long Gastralia with rays twice or more than twice as long 

 as in autodermalia. Oxyhexaster with diameter of 100 — 130 />. ; occasionally 

 hemi-hexactinose, rarely hexactinose. Macrodiscohexaster spherical, 80 — 120 ft 

 in diameter ; with no less than ">, moderately thick, straight terminals to each 

 very short but thick principal ; terminal disc small with minute marginal teeth. 

 Microdiscohexaster of usual shape ; diameter 20 — 2-i ft, — Thick-walled, sack-like 

 sponge with prostal needles and hillocky elevations on external side, so that it 

 closely resembles Acanihascus cachisi. 



Loc. : Sagami Sea. 



I> ACAXTHASCIXiE. 



Autodermalia variable. Hypodermalia with pentactins or exclusively diac- 

 onie Gastralia, hexactins as a rule. Parenchymal megascleres exclusively 

 diactins. Intermedia consist of oxyhexasters and of two kinds of discohexasters, 



o ■/:/.-{■ rs and microdiscohexasters. 



Key to Genera. 



a'. Hypodermal pentactins present. 



I/. Hypodermal pentactinnot pronged Stcutrocnlj/ptua. 



b v . Hypodermal pentactin pronged Khabdocalyptux. 



a". Hypodermal pentactin wanting '.Àcantìuaeus. 



Stau ROCALYPTUS, Ijima. 



Paratangential rays of hypodermal pentactins not armed with hook-like 

 prongs. 



Artificial Key to Species. 



a'. Autodermalia almost exclusively or predominantly pen 

 tactins ; at least with a large number of pentactin«. 



li'. Octaster with radius of 72 - 145 ft S. tlawlingi, 



b''. Octaster with radius of 65—85 ft ; autodermalia slen- 

 der-rayed, often stauractins S, roeperi. 



a". Autodermalia almost exclusively or at least predomi- 

 nantly stauractins. 



I/. Octaster large, usually more than 200 fi in radius. S, glaber. 



W. Octaster small, not larger than 100 ft in radius. 



