SPON&IIDA. 441 



in the slenderness of the bihamate spicules, and the almost absolute 

 absence of a head to the very slender linear spicule ; the resemblance 

 in spiculation seems conclusive as to the generic identity of the 

 three forms, in spite of the remarkable differences in the skeleton. 

 The mulberry-like bodies described by Marshall in P. solida I can- 

 not see in the present species ; when treated with hydrochloric acid 

 the superficial layer of the dermis parts with all hard elements 

 except the spicules and some amorphous transparent fragments. 

 Marshall himself does not mention these bodies ii^.P. reticulum, so 

 that they cannot be of more than specific or individual importance. 



The spiculation of Phoriospongia is perhaps nearer to that of 

 AmpMleetus than of any other genus. Thus, besides Olathria (see 

 0. tuberosa, p. 444), we have a second genus of Siliceous Sponges 

 which may normally exhibit the phenomenon of intussusception 

 of sand into the fibre. It seems to me that intussusception is the 

 most probable hypothesis on which to account for the presence of 

 the sand in this genus, although Marshall, whom I understand to 

 describe Phoriospongia as penetrating and spinning up masses of 

 sand (" durchziehen und umspinnen Sandmassen, sie zu Klumpen 

 vereinigend "), may be right in this interpretation of the origin of 

 the sand in the genus Phoriospongia ; however, in P. fibrosa we 

 find a real system of fibres which does not appear to occur in P. solida 

 and reiicuZum ; and although I have not been able to detect a horny 

 material, like that oi Dysidea, uniting the sand grains, which might, 

 as held by Bowerbank and Marshall, pick them up, it seems to me 

 that, remembering the readiness with which Siliceous Sponges, 

 whether possessing a horny fibre or not, take up foreign bodies, 

 there is no reason why the sand of Phoriospongia should not be 

 taken up,* and not be due to the penetration of masses of sand by 

 the sponge. This View is supported by the spiculation, which is 

 not Suberitid like that of Vioa, but, as above remarked, Desmaci- 

 dine ; the presence of the spinulate spicule is common to it and 

 many Desmacidines ; while the absence of the remarkable eversible 

 funnel which distinguishes the termination of the excretory canal- 

 system in Vioa seems to indicate a difierent afiinity. Benierafibvi- ■ 

 lata, Schmidt, to which Marshall refers in support of his view that 

 bihamates occur in sponges other than Pesmacidinidae, has been 

 placed by Vosmaer in that group under the genus Desmacodes, 

 Schmidt, apparently not without reason ; and Schmidt (Spong. Atl. 

 Geb. p. 40) himself inclines to the view of its Desmacidine affinities ; 

 but the presence of bihamates in Suberitidae is hitherto unknown. 



ECTTONID^. 

 Ectyonida, Carter, Ann. ^ Mag. N. H. 1875, xvi. p. 133. 



Schmidt (Spong. Atl. Geb. 1870, p. 133) grouped Chalinopsis 

 {=Eet'yon) and its allies, with Aooinella, Phacellia, &c., under the 

 heading Chalinopsidinae ( = Echinonemata, Carter, I. c). Mr. Carter 



