lbG7.J DR. J. K. GRAY ON SPONGES. 517 



Var. Spongia scypha, Mont. W. Th. ii. p. 107, t. 15. f. 1. 

 S.foliaceus, Gray. 



See also — 



Phakellia robusta, Bowerb. B. S. ii. p. 126, f. 367 (fan-shaped). 



Subsection 2. S})icular Sponges (Spiculospongi^). Sponge fleshy, 

 more or less strengthened by fasciculated or scattered siliceous 

 spicules, the fascicules being sometimes slightly covered with a 

 thin layer of horny matter. Sarcode generally abundant, gra- 

 nular or fleshy ; sometimes it is mucilaginous and early deci- 

 duous, as in Euplectella. 



Oxyospongice, Ducliass. & Michelotti, Spon. Mer Cara'ibe. 



The three principal families of this group are distinguished by the 

 absence or the presence of certain kinds of spicules ; thus tlie Espe- 

 riadcB have bibaniate "defensive " spicules, whilst the Tethyadce have 

 three-pronged or three-hooked and stellate spicules, and all the 

 kinds are absent in the Ilalichondriadce. 



The Euplectellad(B and Polymastidce are distinguished by tbe 

 textile structure of their tubular l)ody ; the former has several kinds 

 of defensive spicula, which are abt^ent in the latter family. 



Order III. LEIOSPONGIA, or Unarmed Sponges. 



Sponge with all the spicules of the same kind, often varving more 

 or less in size and form, but they are always modifications of the most 

 simple kind of spicules. 



The spicules are not all uniform in shape; but, if varying in shape, 

 they all belong to one type of form. Thus they may be either cv- 

 lindrical, fusiform, needle-shaped or pin-shaped, or any of the inter- 

 mediate modifications of these shapes, which sometimes insensiblv 

 pass into each other. In some of these sponges all the spicules 

 are of one or the other of these modifications ; others contain two, 

 and others again all thrte, of these forms combined together. They 

 are easily known from the sponges of the next order by the entire 

 absence (except in some very rare instances) of any of the spicules 

 that Dr. Bowerbank has called defensive and retentive spicules — that 

 is to say, bihamate, anchorate, birotulate, stellate, or three-pronged 

 spicules. 



The fusiform, needle-like, pin-shaped, and cylindrical spicules be- 

 long to a series, and these forms gradually pass into each other ; that 

 is to say, there are all intermediate forms ; sometimes the spicules of 

 one sponge, or even specimen, present more than one form. These 

 spicules are smooth, or partially or entirely spiculated or tubercu- 

 lated, or they are furnished with smooth or rugose or sj)inous rings. 

 They are rarely angularly bent in the middle, or curved at each end 

 and bent in the form of an S. I have never seen the two ends bent 

 up on one side, such double-hooked spines belong to tlie bihamate 

 series, and are generally undeveloped spicules of that form. With 



