■ 





THE SPONGES. 



33 



erable distance, 60 mm. or so, exhibit the well-known annular ridges. 

 The lower ends are broken off. 



Of the known 



Il/alonema 



35). 



A 



nearest H. conns F. E. Sch. (Schulze, 1887, p. 209; 1893, p. 

 precise point of difference concerns the micro-oxyhexacts which in H. corns 

 have straight and distinctly roughened rays 50-60 p long. The pinules and 

 macramphidiscs are very similar in the two species, although in II 

 pateriferum the macramphidisc umbels are wider and shallower, especially 

 in the specimens from Station 17 (1900 cruise). 











HEXASTEROPHORA F. E. Schulze. 



EUPLECTELLIDAE Gray. 



1841. 



1887. 

 1901. 



Euplectella Owen. 



Euplectella Owen, 1841, pp. 3-5. 

 Euplectella Owen, Schulze, 1887, p. 53. 



" Ijima, 1901, pp. 37-58 



Euplectella, sp. 



Plate 4, Fig. 4, 



3A0A 



The specimens include only the 



dictyonal framework, with no free spicules, and thus a closer identification 



is impossible. 



The specimens represent in all cases the lower part of the body, which is 

 somewhat curved and tapers to the inferior apex. The paragastric cavity is 

 limited below by a " bottom plate." The extreme lower end of the body is 

 worn in most of the specimens, but in one the longitudinal bundles of the 

 wall are continued below the body, curving toward one another so as to 

 form a conspicuous cone, which extends 6 mm. below the bottom plate. 



The wall is made up of the longitudinal, transverse, and oblique silicious 

 strands characteristic of Euplectella, all firmly united together by exceed- 

 ingly numerous synapticula. The longitudinal tracts on the outer surface 

 are strongly, whereas the transverse tracts on the inner surface are 

 feebly, developed. Along the former, and also along the oblique tracts, 

 are here and there developed isolated protuberances, which in places are 

 united to form parietal ridges. The parietal apertures are rounded and 

 for the most part arranged in fairly regular transverse or oblique rows. 





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