DENDY—HOMOSCLEROPHORA AND ASTROTETRAXONIDA 241 



the cortex and either reach the surface of the sponge between the conuli or are continued 

 into the conuli. 



Spicules : — (1) Plagiotrisenes (Plate 47, fig. 1 o) ', with stout shaft and short, stout, 

 often somewhat incurved cladi ; shaft sharply and very gradually pointed, cladi sharp or 

 blunt; shaft about 2'5 by 0"068 mm. ; cladi about 0"14 by 0"04 mm. 



(2) Oxea (fig. 1 b) ; stout, fusiform, straight or nearly so, gradually and finely pointed 

 at both ends or with ends somewhat blunted ; measuring sometimes as much as 4 by 

 0*07 mm. 



(3) Chiasters (fig. 1 c) ; with about eight rather slender, usually slightly roughened 

 rays each ending in a small oval knob (I have seen one specimen with spiny instead of 

 knobbed ends, as described and figured by Thiele) ; usually about 0'02 mm. in total 

 diameter but sometimes nearly twice as much. 



(4) Slender oxea (fig. 1 d) ; straight, gradually sharp pointed at each end, with very 

 faintly roughened surface ; measuring about 0*266 by 0"005 mm. 



(5) Microrhabds (fig. 1 e) ; short, thickly covered with small, short spines ; varying 

 in diameter; say about 0"012 by 0"004 mm., including spines. Especially abundant in the 

 dermal membrane. 



(6) Trichodragmata (fig. 1/); each dragma about 0*03 by 0'012 ram.; readily 

 breaking up into hair-like raphides. Enormously abundant and sometimes collected in 

 large oval or spherical masses, especially in the outer part of the cortex. 



A careful comparison with Thiele's excellent description and figures leaves no doubt 

 as to the specific identity of the " Sealark " with the Ternate specimens. Yet Lendenfeld 

 [1903] speaks of the asters as "oxyasters" (Thiele simply calls them asters), while in our 

 specimens they are chiasters with knobbed ends, the difference between the two being 

 extremely minute ; and Thiele regards the spiny microrhabds as sanidasters ! These facts 

 show the utter hopelessness of basing generic distinctions upon oxyasters and sanidasters 

 as distinct from chiasters and microrhabds. I think a comparison of my figures of the 

 spicules with those given by Thiele will fully justify the identification. 



Previously known Distribution. Ternate (Thiele). 



Register Nos., Locality, &c. lxxviii. 1 a, b, 3, Cargados Carajos, 28.3.05, B. 2, 

 30 fathoms. 



Genus EciONEMiA Bowerbank [1862 c]. 



Stellettidse in which the microscleres include microrhabds in addition to euasters ; 

 the former are commonly minutely spined or roughened and usually form a dermal layer. 

 There are no trichodraofniata. 



I accept this genus in the same sense as that in which I employed it in my Ceylon 

 Pearl Oyster Keport [1905]. I cannot at present enter into the very difiicult and complex 

 question of its relationship to Ancorina and other stellettid genera and sub-genera, but 

 I may say that neither the arrangement of SoUas [1888] nor that of Lendenfeld [1903] 

 appears to me satisfactory. There can be no doubt that the species which I include in' 

 Ecionemia are closely related to E. acervus, Bowerbank's type of the genus. 



SECOND SERIES— ZOOLOGY, VOL. XVII. 31 



