and Nomenclature of Sponges. 165 



the Coral Sponges would be placed near the Euplectelladce, 

 thus : — 



Section I. Malacospor^. Soft-spored Sponges. 



Subsection I. Leiospongi^. Spicules none, or, when pre- 

 sent, of only one kind. 

 Order I. Keeatospongi^ (Horny Sponges), including 



the families Spongiadge &c. 

 Order II. Eaphispongi^ (Needle Sponges) — that is, the 

 order Leiospongiae of my Table, including HaKchon- 

 driadge &c. 

 Subsection II. Acanthospongi-*:. Spicules always pre- 

 sent, of more than one form, akin in each Sponge. 

 Order III. Coealliospongi^ (Coral Sponges). Spicules 

 anchylosed by siliceous matter, as Dactylocalycidse, 

 Aphrocallistidae, Euplectelladee. 

 Order IV. Armatospongi^ (Armed Sponges). Spicules 

 distinct, more or less immersed in horny or fleshy mat- 

 ter. Includes Esperiadge and Tethyad^. 

 Subsection III. Aeenospongi^, or Sand Sponges, &c. 



Dr. Bowerbank has complained to me that I have erro- 

 neously described the Coralliospongige as formed of " siliceous 

 spicules anchylosed together by siliceous matter, forming a 

 netted mass." He says that I have confounded Jibre with 

 spicule. As the siliceous spicules are of the same structure, 

 whether they are short and thick, or very long cylindiical 

 filaments like those of Et(2:)lectellaj I can see no reason why 

 they should not all be called spicules. 



Dr. Bowerbank states that fibres always anastomose and 

 form a network, spicules never do so. According to this rule, 

 some of the spicules of the Euplectella do anchylose and some 

 do not ; so that some should be called spicules and others 

 fibres. Perhaps this is why Dr. Bowerbank speaks of the 

 " long siliceous spicula or fibres of Euplectella " (Brit. Spong. 

 i.p.9). 



Hence Dr. Bowerbank characterizes the Coral Sponges as 

 having a siliceo-fibrous skeleton (B. S. i. p. 203) ; and he re- 

 marks that the structure and mode of growth in this suborder 

 of siliceo-fibrous Sponges " appears to be precisely the same as 

 that of the cerato-fibrous sponges " [ibid.). 



This is true to a certain extent, as the spicules of the sili- 

 ceous and the fibres of the horny sponges are each secreted by 

 the animal and deposited in successive layers, and merely 

 differ in the quantity of animal or horny and of siliceous mat- 

 ter that they contain. Some spicules are almost all silica, 

 with scarcely any horny matter, and some horny fibres almost 



