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clearly defined swelling at the point where the axial cross is situated. They are 

 several (6 and more) mm. long and about 80 /* thick. The angle at which their 

 two rays meet is exceedingly variable. Some of them are nearly straight (angle 

 nearly 180^) others form, according to their position in the reticulating fibres 

 supporting the sieve-plate, a blunt, right, or even an acute angle with curved apex. 

 The spicules lying at the margin of the sieve-plate are usually rectangularly bent ; 

 one of their rays lies in the sieve-plate, the other in the tube-wall. The bulk of 

 the fibres forming the supporting skeleton-net of the sieve-plate does however 

 not consist of these stout principalia, but of the numerous, long and thin comi- 

 talia which form bundles, accompanying and enclosing the principalia. These 

 comitalia closely resemble the comitalia of the tube-wall and are, like them, 

 slender triactines and diactines, the latter however greatly predominating. Rarely 

 similar, long stauractines, pentactines or hexactines are found in these fibres. 

 Shorter and stout, scattered oxyhexactines and oxypentactines on the other hand 

 are pretty frequent. 



Here and there the elongated proximal rays of the rather stout, sword-shaped 

 hexactine hypodermalia also take part in supporting the parenchyme; this is 

 particularly conspicuous in the crests and ridges of the outer surface and in the 

 marginal collar surrounding the sieve-plate. 



Among the parenchymal, microsclere intermedia very tender and thin oxy- 

 hexasters, about 100 ^ in total diameter, are to be mentioned, which occur sparsely 

 scattered here and there. Each of the short and slender main-rays of these 

 spicules bears 3 or 4 slender, slightly diverging branch-rays (pi. XXII, f. 6). 



In the vicinity of the outer surface very few, singly scattered, slender 

 sigmatocoms, which may perhaps lie in the dermal membrane itself, are met with. 

 These measure 80 f in diameter and their rather stout, cylindrical main-rays 

 are about 8 m long. Each mam-ray terminally slightly extends and then divides 

 into 6-8 thin branch-rays. The latter are arranged in a verticil, are curved in 

 an S-shaped manner and together form a calyx of medium breadth. The out- 

 wardly bent basal half is very thin, thread-like, the inwardly-bent distal half is 

 thickened in the middle and terminally pointed (pi. XXII, f. 5). 



I particularly remark that I have not found in this species any of those 

 larger parenchymal graphiocoms, formerly called graphiohexasters, which are 

 met with in or below the dermal membrane in Euplectella wiperialis Ijima and 

 Euplectella oweni Marshall. 



The sword-shaped, hexactine hypodermalia which typically form the main 

 part of the dermal skeleton in all Euplectellidas are met with everywhere below 

 the outer surface. They differ from each other, however, considerably in size 

 and in thickness. Their paratangential and proximal rays are for the most 

 part smooth and only terminally rough or covered with stout spines, their free 

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