8P0NGIIDA. 617 



39. Echinonema gracilis. (Plate LIV. figs. I, V .) 



Erect, very slender, branching dichotomously and seldom ; branches 

 given off at angles of from about (50° to 90°, cylindrical or irregular, 

 sometimes somewhat flattened, diameter 2 to 5 millim. Surface 

 smooth. Vents not apparent. Consistence in spirit soft, elastic, 

 very compressible, rather tongh ; colour very dark purplish brown. 



Main skeleton subrectangular in arrangement ; primary fibres -05 

 to -07 millim. in diameter, pale yellow, almost filled with the skcleton- 

 spicule ; secondaries "035 to *05 millim. in diameter, containing one 

 or two series of spicules. Dermal skeleton consisting of radiating 

 tufts of subspinulate spicules, the bases of the tufts about *25 millim. 

 apart, the points of adjacent tufts crossing each other. Sarcode of 

 interior dark yellow, granular ; that of dermis transparent, very pale 

 purple. Spicules : — (1 ) Subspinulate of skeleton and dermis, straight, 

 shaft smooth, head provided with a few terminal very fine spines; 

 head oval, of about samo diameter as middle of shaft, neck slight ; 

 spicule tapering gradually to sharp point ; size *34 by *012 millim. 



(2) Acuate, minutely spined on base, straight, tapering gradually to 

 sharp point; size -25 by -014 millim. (in centre of primary fibre). 



(3) Echinating spined subspinulate, tapering to sharp point from two 

 or three diameters from end, well spined over head and distal two 

 thirds ; the spines sharp and strong, those on shaft recurvate towards 

 head ; size of spicule -082 by '013 millim. (4) Tricurvate acerate 

 of sarcode, smooth, middle curve bold ; size - 057 by -001 millim. 

 (5) Equianchorate, navicular, shaft slightly curved ; length of spicule 

 •02 millim. 



Hah. Providence Reef, Mascarene Islands, 24 fms. ; bottom, sand 

 and dead coral. 



Several small and more or less imperfect specimens in spirit; the 

 largest measures 75 millim. (3 inches) in length. In the slender 

 proportions of the sponge (which gives it the appearance of a 

 Raspailia) and in the weak development of the horny fibre this 

 species stands quite apart from the Australian species as well as 

 from the foregoing form. 



AXINELLIDiE. 



Of the four species to be enumerated, one is found also on the 

 southern and one on the west northern coasts of Australia. The 

 very variable character of the surface of Leueophlcms proteus is a 

 somewhat unusual manifestation of the polymorphism of Sponges. 



40. Axinella spiculifera. (Plate LIV. fig. b.) 



Spongia spiculifera, Lamarck, Ann. Mus. Hist. Nat. xx. p. 449. 



A specimen in spirit, agreeing well with the fragment in the 

 Museum which represents Lamarck's species. It consists of two 



