68 



THE SPONGES. 



from the base upwards, being 2 



their equator and over their under surface, recurving spines. The upper 

 surface of the head is smooth, or covered with minute prickles into which 

 the recurving spines gradually pass. The rays usually ascend obliquely, 

 and then diverge rather suddenly, but the precise curvature varies. The 

 shaft is like that of the dermal scopulae, and about 300 /x long by 5 xt 

 thick below the upper enlargement. 



The gastral scopulae fall into two classes between which there are 

 transitions. In the one the distal rays are smooth, and gradually enlarge 



/x thick below, 4 /x thick above, then 

 expanding into a large head, 12 /x in diameter, which bears strong recurv- 

 ing spines. In the other form, the distal rays are nearly cylindrical ; 

 roughened with minute denticulations ; and provided with heads which 

 are small, 8 /x in diameter, and feebly spinose. The first form predomi- 

 nates in the specimens from Station 3359, the second form in those from 

 Station 3358. 



It will be seen that in this subspecies there are two extreme types of 

 scopulae, the small dermal form (Fig. 3, Plate 8) and the gastral 

 scopula, with smooth distal rays (Fig. 2, Plate 8). The larger scopulae 



i 



on the dermal surface, and the gastral scopulae with roughened rays, 

 constitute intermediate forms. In the type (Schulze, 1899, p. 75) the 

 dermal and gastral scopulae are alike, and resemble the gastral scopulae 

 of this subspecies, but have spinose rays. 



I 



I 







Eurete erectum mucronatum, subsp. nov. 



Plate 8, Fig. 7. 



Diagnosis. Like Eurete erectum tubuliferum^ but with oxyhexasters instead of ony- 

 chasters. 



Station 3358, 4 specimens ; Station 3359, 1 specimen. 



In this subspecies there are oxyhexasters instead of onychasters. The 

 oxyhexasters are abundant in some specimens, only fairly so in others. 

 The difference is doubtless due to the extent of maceration. The spicules, 

 Fig. 7, Plate 8, vary somewhat in size in the different specimens. In 

 the spicules of one specimen the principal ray is 4-6 /x long, the terminals 

 40-50 /x. In another specimen the principal ray is 4-6 /x long, terminals 

 32-40 /x. In a third specimen the principal ray is 6-8 /x long, termi- 





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HM 



