

• 



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■ THE SPONGES. 



39 



dermalia, to large forms with tangential rays 600 /x ong and 65 /x thick. 

 In the larger ones the tangential rays are commonly of unequal lengths. 

 Some of these stout spicules are found here and there over the general 



surface of the body. 



the description 



The tangential 



The gastralia are scattered. 



Pentacts answering to 



given by Ijima (1901, p. 275) for R. phoenix are common, 

 rays are equal or unequal, and mostly 150 to 250 ^ long by 10 to 12 /x 

 thick. The proximal ray is longer, frequently 500-750 /x by 10-12 /x. 

 Similar tauactines and stauractines are common. Hexact forms also are 

 frequent, like the pentacts except that the small rounded boss is repre- 

 sented by a ray, which is usually much shorter than the tangentials, 

 and is smooth, terminally rounded, cylindrical, or slightly enlarged, the 



Gastralia similar to those 



here described are present in a specimen of R. phoenix from the Museum 



of Comparative Zoology. 



Onychasters are abundant. The principal rays measure 4-6 /x, the 

 terminals about 30 /x in length. The terminals are slender and tapering, 



greatest thickness sometimes reaching 16 /x. 



nix 









usually 3 to a principal. The spicules differ from those of R. phoeni 

 (Schulze, 1899, p. 21, Plate III.; Ijima, 1901, p. 216, Plate X.) in the 

 size of the claws. In R. phoenix, according to Schulze's and Ijima's figures, 

 the claws are fully 2 /x long. In my specimen the claws are 1 xt long 

 and exceedingly fine. The difference, although one of degree, is easily 

 noticed. In a preparation of R. phoenix (specimen in Museum of Com- 

 parative Zoology) I can observe the claws with a power of 300, and can 

 study them very well with a power of 600. In my specimen, with the 

 former power, all the spicules look like oxyhexasters, and even with 600 

 most of them present this appearance. To make sure of their general 

 presence, it is necessary to use an immersion objective. In the spicule, 

 only two claws can be made out on each terminal, and these project 



forwards. 



A floricome is found in the immediate neighborhood of the distal ray 



of each dermal pentact. The spicules are like those of R. phoenix (Schulze, 

 1887, p. 85, Plate XIII. ; Ijima, 1901, p. 276, Plate X.), but the size is some- 

 thing smaller than that given by Ijima, the diameter being about 80 /x. 



G-raphiocomes must be rare. I do not find any in my preparations, 

 and only a very few rhaphides. Nor do I find any spicules peculiar to 

 the border of the parietal apertures. 









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