416 Mr. H. J. Carter on a new Species 



balsam, nor in any others examined, could I find the least 

 trace of any of the minute kinds of spicules which characterize 

 the Hexactinellidfe. Then it must be remembered that, al- 

 though the large spicules of a sponge of this kind might be 

 caught up and preserved by such a " tangle " as the Tethya 

 afforded, the small spicules to which I allude would inevitably 

 escape. 



Fig. 3 is a more magnified view of the central portion of 

 one of the great cruciform peripheral spicules, here introduced 

 for comparison with the fossil fragment (Annals, 1871, vol. vii. 

 p. 126, pi. ix. fig. 37). It is the only part of this spicule which 

 in the hurly-burly of the waves and currents, would be likely 

 to survive all the rest on its way to become fossilized; and the 

 identity is so great that my conjecture, at the page mentioned, 

 of their having belonged to a " quaternate or quadrifid system, 

 whose parallel is only to be found in Hyalonema[Carterin) &c." 

 is thus confirmed. That which I supposed to be an enlarged 

 central canal in the fossil is the original shaft, and the external 

 portion [d) an additional layer, as evidenced by the recent 

 specimen — thus being only an instance of the common mode 

 of strengthening and enlarging the structures of the Spon- 

 giadffi, viz. by the addition of layers to the external surface of 

 the horny or silicified fibre. 



Hence, having found fossilized fragments of this system in 

 the Greensand, the Hexactinellidse cannot be descended from 

 the Ventriculitidae of the Chalk, as Schmidt's pedigree-table 

 (Atlant. Spong. Faun. 1870, p. 83) would have it, in support 

 of the evolution-theory. But as a '^theory" is but a "theory," 

 it is only to correct the mistake and maintain the remaining 

 part until another error is found out, and so on. 



I take this opportunity of stating, in modification of what 

 I have said in my " Fossil Sponge-spicules of the Greensand," 

 p. 126 [op. et loc. cit.), viz. that I had not been able to find 

 any Aeicradiate spicules in my mounted specimens of Hyah- 

 nema^ that since then I have obtained and mounted other 

 specimens from an undoubted Ilyalonema, taken off w^ith my 

 own hands, in which 7ie,xradiate spicules, of minute size, are 

 as plentiful as in any other sponge of the kind. Still I main- 

 tain that, if Hyalonema is to be considered one of the Hexacti- 

 nellidse, it must be based upon the presence of these small 

 hexactinellid spicules ; for the large ones of the periphery, and 

 the minute feathered ones too, there, which appear to be the 

 same in this respect as in Holtenia, bear no trace of the sixth 

 ray, that I can see. Indeed the sixth ray, if on one of these 

 large cruciform peripheral spicules, which appear to be in- 

 tended to bind down the surface smoothly, would, by its pro- 



