54 Mr. H. J. Carter on Specimens 



Colour white or brown. Surface even, divided into irregular, 

 polygonal, placoid spaces varying in size, under half an inch 

 in diameter, slightly concave towards the centre, raised at the 

 margin, where they meet each other, but do not join. No 

 pores and no vents visible over the placoid spaces them- 

 selves, but a line of separation between them where in appo- 

 sition, through which communication with the interior is 

 obtained. Plates or placoid portions crust-like, composed of 

 siliceous globules, like those of Geodia, united together by 

 exceedingly tough fibrous sarcode; subjacent to which is 

 another layer composed of areolar sarcode charged with pin- 

 like spicules, whose points project slightly beyond and between 

 the marginal appositions of the plates respectively ; within 

 which, again, is a solid thick axis, entirely composed of the 

 same kind of siliceous globules as the plates. Spicules of 

 four forms, viz. : — 1, large, pin-like, straight, smooth, shaft 

 subcorneal and abruptly pointed, head globular, as wide as 

 the thickest part of the shaft, 65 by l-1800th ; 2, sili- 

 ceous globule, more or less elliptical, compressed slightly in 

 the direction of a hilous depression, which is on one side ; 

 surface uniformly consisting of minute stelliform points, more 

 or less multifid and in juxtaposition, being the ends of the 

 radiated crystalline structure of which the interior is com- 

 posed, 17 by 13-6000ths ; 3, a much smaller siliceous globule, 

 which is spherical and covered with minute conical points in 

 juxtaposition, that give it a multiangular appearance, 

 3-60Q0ths ; 4, smooth, microscopic, siliceous globules, which 

 appear to be originally developed in cells, about 3-6000ths 

 in diameter. No. 2 (siliceous globule), with which no. 3 

 is sparsely mixed, forms the staple spicule of the hard 

 axis and mail-like plates respectively ; while no. 1, the 

 pin-like spicule, is confined to the areolar sarcodic layer be- 

 tween the two, where it is arranged in glistening tufts, whose 

 points, as before stated, project through the line of separation 

 between the plates. The microscopic globules appear to be 

 chiefly situated in the dermal layer. Size of largest speci- 

 men (for there are two) about 1£ inch long, 8-12ths inch 

 broad, and 4-12ths thick. 



Hab. Marine. Attached to hard objects. 



Loc. Gulf of Manaar. 



Obs. I have partly described this species from the speci- 

 mens in the British Museum, one of which was well figured 

 by Dr. Gray {I. c.) ; but the description not being detailed with 

 that minuteness which this remarkable sponge deserves, has 

 led to my making the above additional statements. It will 

 have been observed that the siliceous globule is identical with 



