REPORT ON THE MONAXONIDA. 95 



As regards spiculation, it will be seen that the species agrees fairly closely with 

 Cladorhiza similis, nobis, though the localities from which the two species were 

 obtained are very widely separated. 



Locality. — Station 332, March 10, 1876 ; lat. 37° 29' S., long. 27° 31' W.; South 

 Atlantic ; depth, 2200 fathoms ; bottom, Globigerina ooze ; bottom temperature, 34°'0. 

 One specimen, in good condition. 



Cladorhiza (f) tridentata, Ridley and Dendy (PI. XX. figs. 9, 9a ; PI. XXI. 

 figs. 16, 20). 



1886. Cladorrliiza tridentata, Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. 



p. 343. 



Sponge (PI. XX. figs. 9, 9a, and woodcut Fig. 4) small, invertedly dome-shaped. 

 Upper surface circular, concave, with slightly inwardly turned margin ; lower surface 

 convex; may be attached. Height 6 mm.; diameter of upper surface 12 mm. 

 Colour in spirit pale greyish -yellow. Texture soft and jdelding. Lower surface 

 even but minutely hispid. Upper surface even and smooth. Dermal membrane 

 most distinct over the smooth upper surface. (Until we found the specimen figured in 

 the woodcut, which, being attached to a stone, gives the true 

 position of the sponge, we thought that the convex surface was 

 the upper one, hence the position given in PI. XX. fig. 9c* 

 should be inverted ; when it was drawn the attached specimen 

 was missing.) 



Skeleton. — (a) Dermal ; a very loose and irregular reticu- 

 lation of megasclera. (b) Alain ; with no distinct fibre, a very 



loose and irregular reticulation of spicules. Very numerous y,,,i,_ciaaorMzai?) tridentata. 

 spicules project more or less vertically outwards from the lower ^^^ZTthe'^lti'lotmlZt 

 surface of the sponge for a considerable part of their length, S unC"l^'fS> 'tl^on^'^x 2!^^''' 

 giving to it its hispid character. 



Spicules. — (a) Megasclera ; of one kind only, viz., long and very slender tylostyli, 

 with only very small heads ; broadest in the middle and tapering very gradually to a 

 very fine point at the apex; size about 07 by 0'0155 mm. (6) Microsclera ; (l) 

 Large, tridentate anisochelse of very characteristic form (PI. XXL fig. 20), with three 

 stout, sharp teeth at each end, deeply separated from one another ; the shaft of the 

 spicule is curved, with large, expanded, wing-like, lateral processes, tapering off" from 

 the large end downwards. Length of spicule about 0'076 mm. These chelate spicules 

 are especially abundant in the dermal membrane on the top of the sponge, forming in 

 places an almost continuous layer. (2) Slender sigmata (PI. XXI. fig. 16), frequently 

 more or less contort, measuring about 0'09 by 0"0032 mm. 



WOODS 

 HOLE, 

 MASS 



