Mr. H. J. Carter on tioo HexactmelUd Sponges. 129 



branched round a hollow axis or stem, which in the horizontal 

 section resembles Ventriculites. 



In the evolution of the lantern-like joint it maybe observed 

 that this commences on a sexradiate spicule (tig. 9, c), the 

 centre of which becomes the centre of the lantern, while the 

 structureless sarcode, which here very much resembles that 

 of the Rhizopoda, creeps crookedly and fungus-like from 

 one point of the sexradiate direct to the other, thus marking 

 out the lines of a trapezium (fig. 9, h). After this, subsidiary 

 pseudopodal prolongations are continued from the fixed ends 

 of the threads respectively to the arms of the sexradiate, which 

 in a reticulated form thus further unite the two and act as ad- 

 ditional stays to the main ones. After this the silicifying 

 sarcode still goes on adding layer after layer to the original 

 structure, until the whole becomes greatly thickened and the 

 interstices of the reticulation reduced to eight spaces as before 

 mentioned, so as almost to obscure the cross of the original 

 sexradiate in the centre, which, although also thickened by 

 the silicifying sarcode, still remains intact. Thus, in short, the 

 sexradiate becomes as much imbedded in the vitreous sarcode as 

 if it were in radiate fibre. 



The fringe of spicules which is or, rather, was (for it now 

 lies in loose pieces about the specimen) attached to the grow- 

 ing margins of the circular and gutter-like openings, is also 

 composed of sexradiates, but much larger than those upon 

 which the lanterns are formed ; and while five of their arms 

 interknit proximally with the body-structure of the wall of the 

 tubular tortuous channel, the sixth is free and very long com- 

 paratively ; while the fringe thus formed is still further length- 

 ened by the presence of many (Pacerates) much thicker and longer 

 than any of the rays of the sexradiate, and which, by their uneven 

 surface, seem to represent that form of acerate, so common 

 among the Hexactinellida generally, in which the spines are 

 long and all inclined one loay — that is, inwardly in situ (fig. 5). 

 Still this is of course conjecture ; for I have never been able to 

 find more than a fragment of the shaft of these, but never 

 connected with any cross piece so as to indicate that they be- 

 longed to a sexradiate spicule. However, the surface is so 

 mutilated that the fragments of this fringe are, as just stated, 

 all loose upon the specimen, and only by their pencil-like form 

 here and there, in which the spicules are held together in their 

 natural position by the dried sarcode, show the manner in 

 which they were arranged when attached to the margin of the 

 circular and gutter-like openings of the tubular channels or 

 passages. 



The rosettes are large (especially when compared with those 



