282 Mr. H, J. Carter on the SarcohexactinelUd Sponges. 



objects in nature. It might be termed "pappiform," flexed and 

 simple, in contra-distinction to another kind, in which the 

 filaments are straight and capitate. A similar spicule, though 

 not so complicated, is arrived at through a similar transition in 

 both the E%q)Jectelkej viz. those forms respectively with and 

 without silicified sarcode ; but here the ends of the filaments, 

 seldom more than 8, are capitate and spined on the outer side, 

 claw-like. This form (the "floricomo" of Bbk., f. 194) also 

 occurs in the two sarcospiculous hexactinellid sponges in the 

 museum of the Jardin des Plantes, named respectively by 

 Prof. W. Thomson Hahrodictyon speciosum and H. corhicula 

 (' Annals,' 1868, vol. i. p. 122 &c., pi. iv. f. 1 e). 



(In Hyalonevia^ too, the birotulate spicule also sometimes 

 takes on a hexactinellid form, which, of course, if possible, ren- 

 ders it a still more beautiful object.) 



But the transition to which I have first alluded seems to be 

 characteristic of RosseUa, and the third or florescent form so like 

 that figured by Schmidt ('Grundziige einer Spongienfauna 

 des atlantischen Gebietes,' pi. i. f. 6), that, in the absence 

 of the " birotulate spicule," it seems to me that Iloltema Pour- 

 talesii must be more nearly allied to Bossella than to Holtenia 

 Carpenterij Thomson, more particularly, too, as the large 

 spicule of the surface (op. cit. pi. i. f. 4) is furnished with large 

 spines, in which it agrees with the same kind of spicule in 

 Bossella antarctica (Ann. 1872, vol. ix. pi. xxi. figs. 1-4) 

 (of course, this genus has been established since the publi- 

 cation of the ' Atlantisch. Spongienfauna ' in 1870) ; while, 

 on the other hand, the minute nail-like spicule with crucial 

 head and plumose shaft which Schmidt figures in connexion 

 with Sympagella mix (oj). cit. pi. i. f. 2), and alludes to as 

 characteristic also of the little specimen of the hexactinellid 

 for which he has provisionally suggested the name of " Hol- 

 tenia saccus^^ {op. cit. p. 15), is, to a certain extent, characteristic 

 of the IIexactinellida3 possessing the hirotidate spicule — but 

 not altogether, as the partial extension of tlie sixth arm, or of 

 the shaft &c., shows. 



The minute, equiarmed, hexaradiate spicule with long irre- 

 gular spines at the ends of the arms in Laharia (No. 5), is also 

 common in Meyerina, and may be the type in these sponges of 

 the " 1st " form of it that I have described in Bossella (p. 281). 

 It is chiefly upon the presence in great numbers of this form, 

 somewhat modified in Hahrodictyon corhicula^ that Prof. W. 

 Thomson has been induced, provisionally, to separate this 

 species from his Hahrodictyon speciosum (Ann. I. c. pi. iv. 

 f. 2 a). But this kind of spicule occurs in too many of these 

 sponges and too much modified ever to be of any specific value. 



