130 Mr. H. J. Carter on 



towards tlie mouth and its inner one directed backwards, to 

 become sunk into the structure of tlie wall ; no. 2, the tri- 

 radiates, are disposed as before mentioned ; and no. 3 is 

 chiefly confined to the surface of the cloaca, where its fourth 

 arm, which is thick, moderately long, and curved towards the 

 mouth, plentifully echinates the surface of this cavity. Size 

 of specinsen about ^ inch high by ^ inch in its widest part. 



Obs. The spiculation in tliis small pear-shaped species 

 generally is, with the exception of the radiates in the surface, 

 comparatively large, and the cribrated sarcode stretched across 

 the boles of the cloaca, although unusual in the calcareous 

 sponges, is not uncommon at the vents of the wow- calcareous 

 ones. In one small specimen, for there are several of different 

 sizes, the peristome is as long as the body of the sponge 

 itself, which is 3-24ths inch, showing that the matured size 

 of the spicules may be independent of that of the sponge. 



The next form to be described is very much like this, but^ 

 in addition to the large curved acerates of the sui'face, pos- 

 sesses co7ies or conical spines formed of a great number of 

 fine spicules like those of the peristome interspersed between 

 them. 



31. Leuconia erinaceus. 



Individualized and social. Specimen pyriform, sack-like, 

 wide above, where it is furnished with a peristome, narrowed 

 to the point of attachment below. Colour whitish yellow 

 outside, sponge-brown within. Surface- sarcode cribriform or 

 reticulate, knitting together the radiates of this part, which are 

 small ; echinated with two kinds of spines, viz. one conical, 

 composed of a great number of fine, long, glistening spicules 

 like those of the peristome, and the other consisting of a 

 single, thick, sickle-shaped acerate, interspersed among the 

 glistening white cones. Pores tlie holes of the cribriform 

 sarcode. Vent single, terminal, circular, provided with a well- 

 marked sarcodic sphincter, surrounded by the palisading of 

 the peristome, which is somewhat everted ; leading into a 

 narrow cloaca! cavity about half the width of the wall in its 

 greatest diameter, which part is opposite the greatest diameter 

 of the specimen, diminishing afterwards towards either end ; 

 covered with a sarcodic membrane presenting circular holes 

 ■which are opposite those of the cloaca ; holes of the latter 

 wide and circular, but variable in size and distance apart, 

 permitting the terminal openings of the canal-system in 

 plurality to be seen within. Wall consisting of cancellated 

 sarcode traversed by the canals of the excretory system ; 

 supported on a skeletal structure consisting of regular and 



