THE SPONGES. 



145 



vertical to surface, and extending from the surface to one of the large 

 efferent canals. The right margin of figure represents surface of sponge. 

 The left margin represents the canal wall) is a reticulum, formed of 

 spinose styles. The reticulum is loose ; meshes commonly squarish, 

 though often subdivided obliquely into triangular meshes. Side of mesh 

 equals length of spicule, and is commonly formed by several spicules (2, 

 3, 4, or even more), making a loose bundle. Continuous bundles, or tracts, 

 more or less radial to the surface, are distinguishable. In places the 

 reticulum might be described as made up of these tracts, with transverse 

 connectives. At the angles of the meshes the spicules are united by 

 spongin. 



The dermal skeleton consists of the superficial layer of the main skeletal 

 reticulum, and of abundant subtylotes. The latter are scattered without 

 order, singly and in loose fascicles, both in the collenchymatous areas 

 of the ectosome and in those parts directly supported by the skeletal 

 reticulum. 



The microscleres occur in the dermal membrane, in the walls of the 

 larger canals, and in the parenchyma in general. They are only fairly 

 abundant. 



Comparative. 



chelifc 



Ridley and Dendy (1887, p. 119). The bipocilli are not only chelate, but 

 in general shape and in size are nearly identical with those of the latter 

 species. The skeletal reticulum in both forms shows vaguely developed 

 fibres, which extend more or less radially to the surface. The spinose 

 styles and tylotes are of about the same size in the two forms. 



Eidley and Dendy describe Iophon chelifer as " amorphous, massive, 

 honeycombed," and add, "Exact form uncertain, specimen fragmentary." 

 The " Challenger " specimens were taken lat. 35° 4' S., long. 18° 37' E., off 

 the Cape of Good Hope; lat. 46° 4r S., long. 38° 10' E., off Prince Edward 

 Island ; lat. 46° 55' S., long. 51° 52' E., between Prince Edward and Ker- 

 guelen Islands; the depth varying from 150 to 550 fath. 



I have examined the type specimens of I. chelifer, and I find that 

 although they are amorphous there is some reason for regarding them 

 as thin plates which, because of the irregular character of the growth, 

 have assumed an amorphous character. Actually, however, they differ 

 markedly in appearance from I. chelifer ostia-magna. While the skeletal re- 

 semblances between my subspecies and the type are very close, the chelate 



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