338 Mr. R. Hope on two new 
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 disappearance 
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 I. strepsitowa. ‘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. J regret much that Mr. Carter is unwilling to describe 
it himself, and it is only because he positively refuses to do 
so 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, and ‘ Challenger ’ Monaxonida, p. 57. 
