Mr. II. J. Carter on two HexactinelUd Sponges. 125 



before it was picked up for preservation, and therefore niiglit 

 have lost, with its sarcodc, most, if not all, of these spicules. 

 But where it is stated, a little further on, that neither Sdero- 

 thamnus nor AphrocaJUstes possesses a rosette, it would have 

 been more to the purpose if Mr. Marshall had said that he had 

 not found any in his specimens, since a knowledge of this kind 

 of sponges points out that the scopuline shaft has hitherto 

 never been found present without a rosette or its represen- 

 tative. Indeed I have stated, from actual observation, that 

 Apkrocallistes Bocatjei has a rosette (Ann. & ^lag. Nat. Hist. 

 1873, vol. xii. p. 300, pi. xiii. figs. 9 and 10) ; and Sclera- 

 thamnus Clausii\ which I now find to be my Farrea densa 

 {op. et loc. cit. p. 51, pi. xvii. figs. 5 and 6), appears in my 

 mounted specimen with its rosettes attached to it, as well 

 as the head and part of the shaft of one of the scopuline 

 spicules. At the time of figuring the fragment of F. densa, I 

 could only be certain of the characteristic spine, as I was not 

 sure that the rosettes and scopuline shafts belonged to it ; but 

 now that I have seen an entire branch, &c., T see also that 

 they do belong to it, and thai Farrea densa [■= Sclerothamnus 

 Clausii) does possess a rosette. When the description and 

 illustrations of the whole specimen, " nearly three feet high," 

 have been published this identity will be more evident. 



The peculiarities of Eurete farreopsis are the globular 

 tuberculated knots of vitreous fibre (fig. 3, bbb), which, with 

 the centrally developed spine, looks like a bossed omphalic 

 shield, and the globular inflations respectively at the ends of 

 the scopuline arms very much like a '' bald head " (fig. 6, c), 

 while the form of the rosette flesh-spicule is that which gene- 

 rally accompanies the scopuline shaft (Ann. & Mag. Nat. 

 Hist. 1873, vol. xii. pi. xiii. fig. 9), occasionally varied, as in 

 the present instance, where the arms are reduced to a mere 

 point and the diameter of the rosette much larger (fig. 3, fj). 

 The acerate spicule (fig. 5), too, with closely applied spines 

 all directed the same way, is still more common among the 

 llexactinellida. To the presence of the minute sexradiate, 

 one arm of which is attached to the vitreous fibre (fig. 3, d d) 

 by an extension from the surface of the latter, I have already 

 alluded as a remarkable feature in this kind of sponge- 

 skeleton. 



Mr. Marshall's criticisms generally of my papers on the 

 Hexactinellida and Lithistida, and on my " Notes introductory 

 to the Study and Classification of the Spongida," respectively 

 {op. et loc. cit.), I have neither time nor inclination to reply to, 

 especially as the author's amount of knowledge of the subject 



