10 ART. 7. T. IJI]\[A : ITEXACTINELLIDA, TV. 



as show the same roughness of siirfnco. It then seems that this 

 shagreen-like character, beginning to arise, whenever it occurs, 

 while the spicule is yet hypodermally situated, does not constitute 

 a constant peculiarity of all old hypodermalia. This opinion is 

 also supported by the fact that the specimen referred to is the 

 only one in which I have seen the rougli peutactins, while in 

 all the rest I have failed to find tlie same sjiicules, whether as 

 prostalia or as hypodermalia, characterized in tlie same way. 



The (lermnlia (PI. I., fig. 4) are rough stauractins, exception- 

 ally and very rarely tauactins ; they are nearly flat or perceptibly 

 convex on the outer side. The rays taper 1)ut little towards the 

 end which is rounded. The prickles on the surface are erect 

 and generally tolerably conspicuous, but are subject to a consider- 

 able variation in this respect according to individuals, as are 

 also the spicules in respect of their size. In most specimens the 

 axial length averaged 220 /'- (the maximum being 280 f) in length 

 and 7 /^ in breadth near the central node. In one specimen, 

 however, I found the average axial length to reach up to 330 f- 

 (the maximum Ix^ing 374 !') ; the rays tapering gradually towards 

 the conically or obtusely pointed end and being beset with rather 

 inconspicuous prickles. F. E. Schulze ('97) had given 160-200 />« 

 as the size of the dermalia. — It is by no means rare to meet, 

 here and there among the dermalia, with perfectly smooth, small 

 and unusually thin-rayed oxystauractins, such as are shown in 

 PL I., fig. "). They are evidently dermalia in an incomplete stage 

 of development. 



The gadrcdia (PI. I., fig. 8) are regularly shaped oxyhexact- 

 jns, measuring 220 — 330 /^ in axial length and Ih /" in average 



