Mr. H. J. Carter on the Suhspherous Sponges. 7 



mens oi Pachymatisma^ I infer that in the fresh state of O. 

 arabica they would also have been much larger and much 

 further apart than in the dried specimen. This difference in 

 size and distance therefore arises from contraction ; and allow- 

 ance should be made for it in viewing the illustration, which 

 is, of course, taken from a dried specimen. 



On raising a portion of the crust of a specimen of O. ara- 

 hica^ and taking out a piece of the subjacent structure (viz. 

 that just inside the trifid heads of the spicules of the zone), I 

 find, by treatment with iodine, that it often contains many 

 decided starch-granules, whose presence seems to indicate that 

 they were developed there, and there in particular, since the 

 part was never so exposed before I opened it, and no por- 

 tions of the structure taken from other parts of the sponge 

 have, under similar circumstances, presented any trace of an 

 amylaceous deposit ; nor have I ever been able to find any 

 starch-granules in a corresponding position of the structure in 

 Pachymatisma Johnstonia. The remark is therefore made for 

 what it may prove worth hereafter. 



TetJiya {Donatia^ Grray) lyncurium^ Lam. 



PI. II. figs. 1-6. 



Globular, almost spherical, fixed. Surface continuously un- 

 even, wartlike, and rigid, except at the part of attachment, 

 which is, of course, rough and torn ; consisting of small, more 

 or less circular lobes, with interangular depressions, the former 

 presenting the broken ends of spicules, and the latter, in the 

 recent state only, the pores and vents respectively of the 

 sponge, which the cortex, owing to its powerfully contractile 

 nature, closes to almost entire obliteration after death. In- 

 ternal structm'C radiated, rigid, compact, consisting of a cortex, 

 body, and nucleus. Cortex defined, thick, rigid, consisting of 

 sponge-fibre interlacing at right angles the spicules of the body 

 as the bundles of the latter pass through it, in an expanded 

 form, to the surface ; the whole so dense as to assume the ap- 

 pearance of fibro-cartilage ; charged with two forms of stellate 

 spicular bodies peculiar to the species. Body consisting of 

 sponge-substance supported on stout bundles of spicules over- 

 lapping each other and radiating from the nucleus to the cir- 

 cumference ; the whole permeated by the excretory system of 

 canals, which, branching and anastomosing throughout, finally 

 terminate in the vents on the surface of the sponge. Nucleus 

 large, globular, consisting of s]:)onge-fibre and spicules, all in- 

 tercrossing and interwoven with each other so densely as, like 

 the cortex, to present the appearance of fibro-cartilage. Spi- 



