284 Mr. H. J. Carter on the Sarcohexactinellid Sponges. 



Lastly, in the rough anchoring-spicules of the glass cord of 

 Hyalonema^ there is a feature well figured by Dr. Gray in his 

 description of this beautiful object, in the ' Proceedings of the 

 Zoological Society,' as far back as 1857 (p. 280), which re- 

 ceives complete elucidation from corresponding spicules in 

 Meyerina and Laharia, and which, from its resemblance to 

 fractured layers of the spicule coming off in ragged circles, is 

 apt to be mistaken for the latter, but which, in Meyerina and 

 Lahariaj is seen to resolve itself into a more lengthened spire 

 of prominent processes like the bracket-steps of a flagstaff, only 

 continuous. This is chiefly apparent on the thickest part of 

 the shaft, and may also be indistinctly observed in Hyalonema ; 

 but on tracing the spiie downwards, or towards the free end 

 of the spicule, the bracket-like processes become each sur- 

 mounted by a spine ; then they pass into distinct separate 

 spines, always recurved or directed towards the sponge, but 

 still maintaining a spiral arrangement, which, lengthening out 

 as the spines become more widely separated, finally ends with 

 the last spine on the shaft. Thus the abrupt part of the spiral 

 line is always directed towards the sponge ; and in a small spe- 

 cimen dredged up on board H.M.S. ' Porcupine,' I observe that 

 this feature is continuous throughout the body of the sponge 

 {Carteria, Gray) to its very summit, where it may serve 

 as much for attachment of the sponge as for anchoring it in 

 the mud — being, too, at this period, as distinctly spined 

 m the sponge-head as any similar spicule of Meyerina or 

 Laharia &c. is out of it ; indeed, here nothing but the form 

 of the terminal hook distinguishes the spicule of Hyalonema 

 at this period from that of Holtenia of a similar size. 



\nEiiplectella\\i& famous "cross" in the central canal of the 

 long-spined spicule shows itself close to the last two spines of 

 the shaft, while the canal afterwards terminates in a lash of 

 branches in tlie midst of the many-spined terminal head. In 

 the spined spicule of Meyerina a cross canal is seen in the head 

 just before the central canal terminates, which may have re- 

 lation to the two spines which are opposite. At all events 

 there is no cross near the last spines of the shaft, as in Euplec- 

 tella. The same is the case in both kinds of anchoring-spicule 

 in Laharia. In Hyalonema I cannot say how the central 

 canal terminates in the ends of the anchoring-spicules, as the 

 only instances I possess are in the mounted specimen to which 

 I have alluded, which does not admit of being brought within 

 quarter-of-an-inch focus, the microscopic power necessary for 

 this determination. 



On the sponges whose horny substance and sarcode is silici- 

 fied, viz. the Coralliospongia?, in part, of Dr. Gray, I hope to 



