SiMiiges from the Atlantic Ocean. 401) 



While the globular tVnin and compact structure generally, 

 if not the great al)iin(Iance of the little globostullate flcsh- 

 spiculcs, liken this sjionge to Geodia, tiie great abundance 

 also of triradiatc antl subquadriradiate spicules mixed toge- 

 ther confusedly (that is, without ajijjarcnt order) also recalls 

 to mind the structure and sj)icules of tlie Calcarea, while the 

 absence of cortex and its massive nature ally it most to the 

 group Litliistina among tlie Pacliastrellida. 



Ot course, where there is only one specimen of a sponge to 

 describe from, as in this instance, a wide margin must be given 

 to differences of general form which may be found to occur after 

 a large number have been examined; but tliis docs not aftect 

 the composition. 



The form of the acerate skeleton-spicule being the same in 

 P. ami/(/'laIoiWes and I\ geodioides, only one illustration 

 (PI. XIV. figs. 22 & 23, A, I, respectively) is given for both ; 

 but it should be remembered that this spicule is three times 

 as large in the former as in the latter, where it also varies 

 greatly in size. 



Pachast reiki tntexta, n. sp. (PI. XV. fig. 41.) 

 Indicated by the presence of a circumscribed light discolo- 

 ration in an old brown, dead, thick, flat fragment of Cbra/^/^^e^ 

 Bowerhanhii, dredged up in 374 fathoms at station 25, a few 

 miles north of Cape St. Vincent. 



Althougli the specimen of this sponge is insignificant in 

 extent, having been discovered almost by accident while ex- 

 amining microscopically different-coloured patches on the frag- 

 ment of Corallistes mentioned, its spicules furnish a new species 

 of Pachastrella, consisting, like all the rest, of two kinds, viz. 

 skeleton- and tlesh-spieulcs. Skeleton-spicules of two forms, 

 viz.: — 1, linear and branched; linear spicule long, acerate, 

 curved, smooth and sharp-pointed, which having only been 

 observed in a fragmentary state from the portion of Corallistes 

 among whose spicules the sponge has grown, having to be 

 dug out with the point of a penknife for examination, its 

 measurements have not been ascertained : 2, ramular or radiate 

 skeleton-spicule, consisting of a straight smooth sliaft, jwinted 

 at both ends, from the centre of which, or thereabouts, branch 

 off three arms at equal distances from each other, wliich become 

 bifurcated and often trifurcated (PI. XV. fig. 41) ; arms 44- 

 GOOOths inch in total diameter, slightly inclined forwards ; 

 viewing the fifth ray as an anterior prolongation of the shaft, 

 which is altogether subsidiary in size to the rest, the arms and 

 their branches are the most striking part. Flcsh-spicules of 

 two forms, viz.: — l,bacillary, slightly undulate, presenting 

 Ann. d: Afa(j. N. Hist. ^cr. -i. IW. xviii. 2« 



