242 I. IJIMA : HEXACTINELLIDA. I. 



fair numbers. Intnct graphiocomes with terminals that had not 

 3^et reached their full-length (PL VII, fig. 9) were several times 

 met with. No other hexaster-form has been found in these little 

 specimens. 



What systematic position to assign to the specimens was at 

 first a great puzzle. The presence of pentactin dermalia seemed 

 to make against tlieir being regarded as Euplectellids, while the 

 graphiocome pointed to their being at least a close ally of that 

 family. Fortunately, however, I have found other young speci- 

 mens which seem to represent transitional stages that lead over 

 the simple spiculation of those little specimens into the more 

 complicated system of the mature R. ohinoseana. 



2. From still another skeletal stump of R. okinoseana (Mus. 

 No. 41)0, from Inside Okinose, March 1898) was taken a young 

 specimen of an elongate ovoid shape, 15 mm. long and 7-9 mm. 

 broad. It is therefore considerably larger than the largest in 

 the last described lot. A simple osculum, 2^2 mm. in diameter, 

 is situated in the upper end. The dermal surface is no longer 

 smooth but uneven. This is caused by the presence of small 

 depressions, several of which have broken through the wall, while 

 many others still remain closed. There can be no doubt that 

 we have here to deal with the first formation of parietal oscula ; 

 the mode of their origin is essentially the same as iu ^uplectella 

 (p. 105). 



Examination of the spiculation also shoAved points of de- 

 cided advance from the state noted in the last lot of specimens. 

 The pentactin-dermalia present exactly the same characteristic 

 features as in the latter. Only, mixed amongst them are oc- 

 casionally found sword-shaped hexactin-dermalia, the distal hilt- 



