G THE VOYAGE OF H.M.S. CHALLENGER. 



Similar individual descriptions became gradually more numerous, and up to 1860 

 the following may be noted as most important : — Dactylocalyx pumiceus, Stuchbury,* 

 1841, Euplectella asjKrgilluin, Owen,^ 1841, Farrea sp., Owen,* 1857, Aphrocallistes 

 beatrix, Gray,* 1858, and Myliusia callocyathus, Gray,* 1859. 



A more profound study of the skeletal structure of Hyalonema sieholdii was made in 

 1860 by Max Schultze.® He also discovered, in those spicules which did not externally 

 exhibit a cruciate or stellate, but merely a simple rod-like form, an intersection of the 

 axial canals in a median swelling, whieli indicated the fundamental stellate type of all 

 the spicules. He was also the first to discover the close affinity of Hyalonema and 

 Etiplectella, which, on account of the common character of the spicular tuft, he united in 

 the group " Lophospongite." 



Bowerbank'^ (1862) was less fortunate in hia perception of the affinities of the 

 Hexactinellid genera known to him, viz., Alcyoncellum [Euplectella, Owen), Quoy and 

 Gaimard, Hyalonema, Gray, Dactylocalyx, Stuchbury, and Farrea, Bowerbank. For 

 while he placed the genus Alcyoncellum, Quoy and Gaimard (with Euplectella, Owen, in 

 parenthesis), in his suborder Silicea with sjyiculo-radiate skeletons, between Ecionema, 

 Bowerbank, and Polymastia, Bowerbank, he referred the genus Hyalonema, Gray, to 

 another quite different suborder, characterised by spiculo-reticulate skeletons, between 

 Halichondria, Flemming, and Isodictya, Bowerbank. Of each of the two genera, 

 Dactylocalyx, Stuchbury [ = Iphiteon, Mus. Paris), and Farrea, Bowerbank, he 

 made, on the other hand, a special suborder, of which the former was characterised 

 chiefly by solid siliceo-Jihrous, and the second [Farrea) by canaliculated siliceo-fibrous 

 skeletons. 



In Gray's System of Sponges,^ which appeared in 1867, the Hexactinellida then 

 known were not yet united into a common group. For while Gray placed the family of 

 the Euplectellidse, consisting of Alcyoncellum and the closely allied Euplectella, with his 

 Esperiadse and Tethydse, in the order of the Acanthospongise (with spicules of more than 

 one form or kind in the same Sponge) and within the subsection Sjjiculospongise (with free 

 spicules), on the other hand he united the family of the Aphrocallistidpe, consisting of 

 the genus Aphrocallistes, with the family of the Dactylocalycidse, including Dactylocalyx, 

 Stuchbury, Myliusia, Gray, MacAndrewia, Gray, and Farrea, Bowerbank, in a special 

 order, " Corallispongise," within the subsection " Dictyospongise " (in which the skeleton is 

 formed of a continuous siliceous or horny network). The Corallispongias were charac- 

 terised by Gray as : — " Hard, coral-like Sponges, entirely formed of siliceous spicules, 

 anchylosed together by siliceous matter into a network. Mass covered with a thin coat 

 of sarcode when alive." 



' Proc. Zool. Soc. Land., vol. ix. pp. 86, 87. ^ Proc. Zool. Soc. Load., vol. ix. pp. 3-5. 



3 Trans. Linn. Soc. Land., vol. xxii. pp. 117-124. '' Proc. Zool. Soc. Land., vol. xxvi. pp. 114, ll.";. 



5 Proc. Zool. Soc. Land., vol. xxvii. pp. 437-440. '' Die Hyalonemen, 1860, 4. 



7 Phil. Trans., vol. clii. 2 pp. 747, 830, 1087. » Proc. Zool. Soc. Land., 1867, pp. 117, 492, :001. 



