94 AKT. 1. 1. IJIMA : HEXACTlNELLTDA, III. 



ijig rays are exactly comparable to the corresponding rays of 

 dermalia, except in the fact that they are perceptibly longer. 

 Length of paratangentials 110-132/^; that of the distal ray 88- 

 100/^. The paratangentials are so arranged as to bring about a 

 rectangularly meshed latticework, in the same manner as those 

 of the dermalia. 



The hexader of the species consists of rough and thick-rayed 

 discohexasters — evidently the pachydiscohexaster of other Caulo- 

 phacus species — and their variations. Lophodiscohexasters are 

 not present. 



As the starting point of our description may serve the 

 spherical or nearly spherical, normally developed discohexasters 

 shown in fju;s. 4 and 5. Such a form occurs, too;ether with 

 certain varieties soon to be mentioned, in tolerable abundance in 

 both the subdermal and subgastral regions, more commonly in 

 the latter than in the former. It measures 60-92 /^ in diameter. 

 In the larger and well developed cases (fig. 5), the principals 

 are obsolete, making it difficult to determine the number of 

 terminals borne on each. However, the usual number seems to 

 be 3 or 4, perhaps occasionally 5. In smaller specimens of the 

 hexaster (fig. 4) the piincipals are only just long enough to be 

 distinguishable and each bears only 2, at most 3, terminals. In 

 all these cases the terminals are thick (up to 4 /^- in breadth) 

 and nearly straight or l)ut slightly bent ; they are profusely 

 beset, throughout their length, with rather strong, retroverted 

 prickles. The convex terminal disc exhibits 4-6, strong, recurved, 

 marginal teeth. 



The form just described is occasionally hemihexactinose (fig. 

 6) and frequently hexactinose (figs. 7 and 8). The hexactinose 



