162 THE VOYAGE OF H.M.S. CHALLENGER. 



EcMnoclathria carteri, Ridley and Dendy (PL XXIX. figs. 12, 12a; PI. XXXI. 

 figs. 3, 3a). 



1886. EcMnoclathria Carteri, Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. p. 476. 



Sj)onge (PI. XXXI. fig. 3) cylindrical, ramose, each branch consisting of flat, ribbon- 

 like trabeculse, anastomosing and interwoven so as to form a loose, honeycombed whole, 

 with rounded meshes on the surface about 2 mm. in diameter. The largest .specimen 

 is about 250 mm. long; diameter of branches about G to 15 mm. Colour in spirit pale 

 yellow. Texture (of the individual trabeculse) tough and compact. Surface very 

 minutely hispid. Dermal membrane thin, transparent, very rarely found stretching 

 across the meshes on the surface. Oscula (PL XXXI. fig. 3a, o) minute, scattered 

 over the trabeculse. 



Skeleton.— k. rather close reticulation of strongly developed horny fibre, cored and 

 echinated by stylote spicules of one kind only, though the spicules within the fibre seem 

 to be usually slenderer than those outside. 



Spicules. — (a) Megasclera ; (l) smooth, sharply and gradually pointed styli 

 (PI. XXIX. fig. 12a), not markedly constricted above the base; measuring about 0"132 

 by 0'009 mm.; in the fibre, irregularly echinating the same, and scattered. (2) Long, 

 smooth, very slender subtylostyli (PL XXIX. fig. 12), measuring about 0"16 by 0'002 mm.; 

 irregularly scattered, (b) Microsclera; of one kind only, viz., smaU, palmate isochelse, 

 very abundant in some specimens, about 0"015 mm. long. 



This is an exceedingly remarkable species. It might be thought that its peculiar 

 external form would be quite sufiicient to distinguish it from all other sponges, but there 

 is a digitate variety of Carter's Echinoclatliria favus (one of the types in the British 

 Museum referred to by him,^ and labelled 37. 5. 13. 36. and 208 bis), also from South 

 Australia, which very closely resembles it. As regards external appearance the two may, 

 however, be distinguished by the fact that in EcMnoclathria carteri, nobis, the anasto- 

 mosing trabeculse usually present a flat surface towards the outside, while in Echino- 

 clathria favus, Carter, they usually have their edges turned outwards. On examination 

 with the microscope the two are more readily distinguished, for Echinoclathria favus 

 possesses few or no cliel^, and there are also other slight diS'erences in spiculation w'hich 

 will be seen by reference to the descriptions. 



Localities.— ^tut'ion 162, April 2, 1874 ; lat. 39° 10' 30" S., long. 146° 37' 0" E.; Bass 

 Strait ; depth, 38 fathoms ; bottom, sand and shells. One or two specimens. 



Station 163a, April 4, 1874 ; lat. 36° 59' S., long. 150° 20' E.; south-east Australia; 

 depth, 120 fathoms ; bottom, green mud. Three or four specimens. 



OS" Port Jackson ; depth, 30 to 35 fathoms. One specimen. 



1 Ann. and Mag. Nat. Hist., ser. 5, vol. svi. p. 292. 



