338 Mr. K. Hope on two neio 



Greensand containing spicules which appear to be identical in 

 shape with the toxa of our sponge, but of much larger size. 

 By Mr. Carter's kindness I am afforded the opportunity of 

 inspecting this specimen. 



The spicules in question are five in number and appear as 

 opaque white bodies in the semitransparent matrix ; in no 

 case does the full length of both arms appear to be preserved, 

 and the ends are by no means sharply defined, but apparently 

 fade away into the stone in consequence of the disap])earance 

 of the white matter which renders them visible. One of these 

 spicules measures about 1"6 millim. in length from the centre 

 of the sinus to the end of one arm ; assuming that it possessed 

 another arm of equal dimensions, of which now but a portion 

 is visible, the total length would reach 3'2 millim., or about 

 eight times that of the toxa of M. strepsitoxa. The arms are 

 straight and horizontal and the central sinus abrupt and 

 semicircular in shape ; the conditions of preservation are not 

 sufficiently good for smaller details to be clearly seen. The 

 other spicules preserved in the stone, which are numerous, 

 are mostly Tetractinellid in character. 



It is proposed to deposit a portion of the specimen of Micro- 

 ciona strepsitoxa above described, together with microscopical 

 preparations of it, in the Natural-History Department of the 

 British Museum. 



The other sponge to be described I received from Mr. H. J. 

 Carter. I regret much that Mr. Carter is unwilling to describe 

 it himself, and it is only because he positively refuses to do 

 60 that with much diffidence I undertake the task at his 

 request. In this undertaking I have the great benefit of 

 Mr. Carter's advice and assistance ; but he is not responsible, 

 except when it is expressly so stated, for any views which 

 may be put forward. 



I refer this sponge very doubtfully to the genus Trachyte- 

 dania^ Ridley * ; it will be most convenient to describe it first 

 and discuss afterwards the points in which, as it seems to me, 

 it agrees with, and those in which it differs from, the charac- 

 teristics of this genus. 



Trachytedania (?) echinata, n. sp. 



The specimens sent me are three, all in the dry state, viz. 

 one, the largest, in a cup-shaped hollow of a piece of red sand- 

 stone rock, measuring 23 x 18 millim. ; another, smaller, also 



* Proc. Zool. Soc. 1881, p. 122, aud ' Challenger ' Monaxonida, p. 57. 



