352 Mr. II. J. Carter on the Hexactinellida?. 



(Annals, vol. ix. p. 430, pi. xxii. fig. 16, June 187.2). The 

 ornamental parts, such as spines c^'c., although no doubt 

 in the original design, are not attended by any alteration in 

 the central canal, and therefore do not belong to the " spicide 

 lyrojperr I call the " spicule proper" that fundamental form 

 which is marked out by the central canal and its branches ; and 

 these do not run into the ornamental portions. 



But whatever may be the terms finally adopted for the 

 spicular systems of the Hexactinellid^ and Lithistidte respec- 

 tively, it is perfectly evident tliat in the grouping of these 

 sponges we cannot include the sarcospiculous Hexactinellida, 

 viz. Hyalonema &c., under either of the terms " Corallio- 

 spongia" or " Vitrea ;" while the name " Hexactinellidge " 

 refers rather to the elements than to the general character of 

 these sponges. 



All sponges begin their development from the ovum in the 

 form of a sarcodic embryo ; after which come the spicules, 

 and lastly the fibre, which converts the skeleton-spicules into 

 an axis, whether this fibre be viti-eous or homy. Hence, as 

 the sarcodic precedes the viti-eous state, the latter would rank 

 as a superior development to that of the sarcospiculous Hex- 

 actinellidge, in which the sarcode never passes into either homy 

 or vitreous fibre, but remains simply hardened and amorphous. 

 So it seems to me desirable that we should discard this 

 " order " altogether, and distribute the groups of the Hexacti- 

 nellidse among the divisions of the Spongiadfe in accordance 

 with wdiat I have proposed in the footnote to my paper on 

 the points of distinction between the Spongiadge and Foramini- 

 fera (Annals, vol. xi. pp. 355-356, May 1873). 



To understand this suggestion, however, it is necessary to 

 premise that the vitreous fibre of the Hexactinellidfe is merely 

 homy fibre silicified, and that the spicules of the species are 

 imbedded in this, after the same manner respectively as they 

 are imbedded in the fibre of sponges generally. This being 

 the fact, we might expect to find certain Hexactinellidge with 

 their spicules all confined to the interior of the silicified fibre, 

 as the spicules in the horny fibre of my third division, viz. the 

 " Chalinida3 " — then that the fibre in another group of the 

 Hexactinellidai is more or less echinated with spicules in 

 addition to those contained in the interior, as in my fourth 

 division, viz. the " Armataj " — or the spicules supported by 

 amorphous sarcode alone, as in the fifth division, viz. the 

 " Renierinas," wherein, too, would come our quadriradiate 

 system, or Schmidt's " Lithistidge," in which I think the 

 filigreed terminations of the amis interlocking with each other, 

 rather than the presence of vitreous fibre, chiefly bind the 



