Sponf/rs from tin' Athinti<- ()i;'iiii. ^^93 



('Ann.' 1S70, vol. vi. |). 17S, j.l. xiii. li'^^^. 1 1, S:c.), also csta- 

 lilisliiui; (lie i^HMius at tlif sanu- liinc 



< )tliL'rs ot' a likt' iiafiin' I'xist in the Brifisli Miiscuin t'loin 

 l*ort Klizalu-th in S. Africa ; and lately .Mr. W. .1. SolJas lias 

 j^^ivon nio halt' of one, in form like a little holster (viz. cylin- 

 <lrioal and slii^htly constricted in the middle), said to have 

 come from Australia. It is /> inches loni; and 2 inches thick. 

 Those which 1 liavc hitherto seen vary under this size, are 

 more or less globular, .and each attached to a little stone. 

 They are {nfensc/i/ hard and tough, grey outside and light 

 yellow within, presenting a iiniforndy round form and stift' 

 villous surface, with no appearance of vents, or at least, if any 

 of the latter, very small, numerous, and indistinct. Internally 

 the structure is fibrous, radio-rctieulate, traversed through the 

 interstices by the excretory canal-system, which is evident 

 enough here. As the branched reticulation radiates from the 

 centre, which is not nucleated, the tibre of which it is com- 

 jiosed becomes smaller and the interstices closer until a little 

 before it arrives at the circumference, where it is lost in a 

 dense mass of spicules that terminate in the villous surface of 

 the dermis. The spicules of which the reticulated structure 

 an<l the body generally are composed are smooth, slightly 

 curved, and fusiform, rounded or intiated ])in-like at one end 

 and more or less pointed at the other, faced by a smaller but 

 like form at the circumference, where there is no cortcv 

 beyond the more densely packed state of the general sti-ucture. 

 My observations under Trachya pernuc.leata (l, c.) are equally 

 applicable here ; and tliese sponges, of which there may be 

 several species, will probably have to be considered a solid 

 G'rodia-Wkc form of Folt/mastia, very nearly allied to the 

 Donatina, and all belonging to the suborder Suberitida. I 

 am very much inclined to think that although in some of the 

 •species the s])icule appears to be acerate (that is, finely ])ointed 

 at hofh ends), a microscopical {)0\ver of about 400 would show 

 that one end is slightly obtuse — that is, leading to the acuate 

 and ])in-like forms with fusiform shafts of most of the species. 

 When one end of a linear spicule is rendered thus obtuse, it is 

 always at the expense in length of this half of the spicule, .so 

 that the maximum inflation of the .shaft is thus thrown out of 

 the middle and nearest to the ol)tuse end. 



Polymastia stipitatuy n. sp. 



General form consisting of a head and long stem. Head 

 round at first, then olx)void with a j)a])illary eminence on one 

 .side of the large end; afterwards cylindrical, expanded upwards, 



Ann. (f* Mny. X. I list. Sor. 4. Vol. xviii. 27 



