A NEW GENUS OF THE HEXACTINELLID SPONGIDA. 



227 



Ks. 2. 



of this sarcode in drying and subsequent partial destruction of it by nmcedinous fungi. 



They thus now appear in little detached masses without any definite arrangement, 



although, here and there, in the dry sarcode which holds them together, a circular hole 



may be seen indicative of their position and office in supporting the internal porous sar- 



codic expansions during the lifetime of the sponge. 



Indeed the sarcode generally has been destroyed 



throughout this sponge in this way, and now only 



hangs in small fragments here and there in the 



otherwise naked fibre (consult portions figs. 11 & 



12). Such, he observes, is the fate of most sponges 



under these circumstances, especially if they are 



exposed to dampness owing to the salt-water not 



having been entirely soaked out of them at the 



commencement. 



4. Spicular Rosettes (figs. 24&25). — Mesh-spicula 

 of the rosette type obtain, and, as in the preceding, 

 are likewise of two forms, a small and a large kind. 

 (a) In this the small rosette or staple form (fig. 24) 

 the figure is relatively globular, and is ^s i nc h in 

 diameter. It consists of six straight, smooth arms 

 parting at right angles from the centre, each arm 

 terminating in a little discoid inflation from which 

 spring four to eight rays spreading in what Carter 

 terms a "fleur-de-lis " (" Hexactinellidse and Lithistiche," Ann. & Mag. Nat. Hist. 1873, 

 vol. xii. p. 355 ; the spinulo-multifurcate hexradiate stellate spiculuin of Bowerbank, 

 Monog. Brit. Spong. vol. i. p. 259, pi. viii. fig. 192). Each ray terminates in an inflation 

 which is expanded into a circular convex head bordered by four spines opposite and 

 recurved. These rosettes (a) are chiefly congregated about the angle of the dermal 

 meshwork and relatively numerous. 



(b) The large rosettes (fig. 25), contrariwise, are very rare, and still more globular in 

 appearance, whilst they range from -^g to -gV inch in diameter. Their centre or, so to 

 say, nucleus appears to consist of six short, stout arms, each arm terminating in a qua- 

 drangular inflation, from which radiate several long straight rays. The rays themselves 

 (very rarely met with bifurcate) end in a quadrangular or more often pentangular cap or 

 head (fig. 26), with free convex surface, but provided with recurved spines at the angles 

 of the opposite surface. This kind of rosette resembles the so called " multiradiate 

 spicula of the sarcode " of Askonema setubalense, Kent (Monthly Microsc. Journ. 1870, 

 p. 246, pi. lxiv. fig 9). 



5. Sexradiate or Dermal Hexactinellid Spicula (figs. 20 and 23, and in position figs. 3 

 and 9). — These forming by the coalescence of the adjoining spicula the delicate veil 

 latticework or rectangular dermal meshwork, have already had passing allusion called 

 to them when speaking of the exterior characteristics. The six arms part at right angles 

 from the centre, the horizontal ones being jjq inch long; the vertical are shorter. 



SECOND SERIES. — ZOOLOGV, VOL. I. 2 H 



Diagrammatical representation of the pro- 

 bable mode of arrangement of the scopuline 

 spicula of Steere's sponge, after a pen-and-ink 

 sketch by Mr. Carter. Sarcode membrane, 

 perforated by pores, may have stretched be- 

 tween the spicular bars and quadrangular 

 spaces, that is, when the sponge was alive. 



