350 Mr. H. J. Carter on the Hexactineliidse. 



revealed, together with a description of a new species of 

 Farrea and a new genus of vitreous sponges. 



I must here premise that whatever value the contents of 

 this paper may possess is all due to the unceasing exertions 

 of my friend Dr. J. E. Gray to place before me all the oppor- 

 tunities in his power, and afterwards to urge me to publish 

 my observations. 



In 1867, Dr. J. E. Gray proposed the term " Coralliospongia" 

 for a certain group of sponges (" Notes on the Arrangement of 

 Sponges," Proc. Zool. Soc. Lond. 1867, p. 505), as follows : — 



" Order I. Cokalliospongia. 



" Sponge hard, coral-like. Skeleton entirely formed of 

 siliceous spicules anchylosed together by siliceous matter, 

 forming a netted mass covered with sarcode." 



Nothing can be more appropriate, both in name and defini- 

 tion, than this diagnosis. Dr. Gray had before him in 

 particular the great, stony, shallow, expanded, stalked, dish- 

 shaped masses of Dactylocalyx pumiceus, Stutchbury (P. Z. S. 

 1841, p. 86), and that of MacAndrewia azorica described by 

 himself (P. Z. S. 1859, p. 438, pi. xv.), both in the British 

 Museum, and each more than a foot in diameter. 



In 1869, Dr. Bowerbank published his " Monograph of the 

 Siliceous Sponges " (P. Z. S. May and June 1869, parts i. & 

 ii. pis. xxi.-xxv. & pis. iii.-vi.), in which we find details of 

 the same specimens, appearing respectively under the names of 

 " Dactylocalyx pumiceus " and " Dactylocalyx MacAndrewii. 11 



So far as the term " Coralliospongia " goes, Dr. Gray was 

 right ; but the details of Lens Aldous's figures in Dr. Bower- 

 bank's monograph show that MacAndrewia azorica might be 

 a family of that order, but could not be a species of Dac- 

 tylocalyx — that is to say, that the elements of Dactylocalyx 

 pumiceus are those of a sexradiate sponge, while those of 

 MacAndrewia azorica belong to a quadriradiate system. (I 

 call the " quadriradiate system " that in which the shaft of 

 the spicule divides into three branches, as in the Geodinidse, 

 more typically shown in the four-armed spicule of Pachastrella, 

 where, the arms being nearly equal in length, that which 

 might be termed the " shaft " is often hardly distinguishable 

 from the rest.) Yet Dr. Bowerbank has changed the name 

 of " MacAndrewia azorica " to " Dactylocalyx MacAndrewii" 

 thus erring both in grouping and nomenclature. 



At the same time Dr. Bowerbank has distinctly shown in 

 his figures, although he has not recognized the fact in his 

 descriptions, that there are two systems, and that while sexra- 



