Sponges from the Atlantic Ocean. 409 



While the globular form and compact structure generally, 

 if not the great abundance of the little globostellate flesh- 

 spicules, liken this sponge to Cfeodia^ the great abundance 

 also of triradiate and subquadriradiate spicules mixed toge- 

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

 to mind the structure and spicules of the Calcarea, while the 

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

 group Lithistina among the Pachastrellida, 



Of 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 this does not affect 

 the composition. 



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

 P. amygdaloides and P. geodioides^ only one illustration 

 (PL XIV. figs, 22 & 23, h, 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. 



Pachastrella intexta, n. sp. (PI. XV. fig. 41.) 

 Indicated by the presence of a circumscribed light discolo- 

 ration in an old brown, dead, thick, fiat fragment oWoraUistes 

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

 miles north of Cape St. Vincent. 



Although 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 flesh-spicules. 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 shaft, pointed 

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

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

 bifm'cated 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. Flesh-spicules of 

 two forms, viz. : — 1 , bacillary, slightly undulate, presenting 

 Ann. & Mag. N. Hist. Ser. 4. Vol. xviii. 28 



