92 AKT. 1. 1. IJIMA : HEXACTINELLIDA, III. 



The derinalia (fig. 3) are exclusively liexactiiiic pinnies, so 

 far as those of the body proper are concerned. The pinular ray 

 as a whole is spindle-shaped ; it is 120-140/^- long and 80-42,« 

 broad in the middle, which is about the broadest part. In this 

 part, the obliquely upwardly directed, elongate conical spines 

 may be as long as 23 JJ-. 'J'he rhachis is smooth for a short 

 distance at the base, wdiich is about 11/'- thick; its conically 

 pointed, outer end forms the tij) of tlie pinular ray. The 

 remaining five rays are all more slender, and gradually taper 

 towards the conically or bluntly pointed end. They are beset 

 with small, generally erect prickles, sparingly at the base but 

 more numerously at the end. Length 88-120«. The proximal 

 ray is usually slightly shorter than the paratangentials of the 

 same pinule. As is usual, two paratangentials of every two 

 adjoining pinnies lie side by side for nearly their entire length, 

 the result being the fine, quadrate-meshed dermal latticework 

 (fig. 19), in which each mesli has sides approximately equal in 

 length to that of the rays concerned in inclosing it. As ascertained 

 on sections, the said latticework does not lie in direct contact 

 with the underlying hypodermal paratangentials but is separated 

 from these by a space about as wide as, or slightly less wide 

 than, the length of the dermal proximal rays (fig. 18). 



Here and there among the dermalia of the bodv I have 

 met with such forms as may appropriately be regarded as early 

 stages of their development. They are comparatively small and 

 slender-rayed hexactins, in which the distally directed (the future 

 pinular) ray is not at all or but little difterentiated from the 

 other rays, being nearly as prickly as these. 



In the upper part of the stalk, the pinnies retain the characters 

 described above ; but they are here much more closely packed 



