282 Mr. H. J. Carter on known Fossil Sponges. 



based upon a sexradiate type, coring vitreous fibre or lield 

 together bj spongin only. 



Order VIII. Calcarea. 

 Possessing calcareous spicules only. 



Now with reference to the first order, which I divided 

 into Halisarcida (possessing no spicules) and Gumminida 

 (possessing spicules), it could hardly be expected that the 

 first division would be perpetuated in a fossilized state, or if 

 so not recognizably, seeing that in the fresh state they are of 

 gelatinous softness and their sponge nature can only be deter- 

 mined by the microscope before they pass into decomposition 

 (which is very rapid), or when kept under the influence of a 

 preservative fluid. 



But this does not apply to the second division, where, to 

 the "gelatinous softness," perhaps a little inspissated, is 

 added an abundance of spicules which more or less resemble 

 those of other sponges, especially some of the HoLO- 

 RIIAPHIDOTA in my sixth order. Thus vve find Chondrilla 

 phyllodeSj Sdt., possessing a spiculation that hardly differs 

 from that of Sjnrastrella cunctatrixy Silt., which is a member 

 of my family iSuberitida (see also my assimilation of 8ube- 

 rites domuncula^ Sdt., to Chondrosia reniformis in my order 

 Caenosa, 'Annals,' 1881, vol. viii. p. 255). One could hardly 

 expect under fossilization either one or the other species to 

 present more than a heap of spicules of the same kind, with 

 perhaps a trace of the canal-structure. But who has found 

 " either one or the other," or how could they be distin- 

 guished ? 



When we consider that the spiculiferous Carnosa may in 

 a fossilized state be hardly more than an almost shapeless 

 mass of the same form of spicules, it reminds me of my 

 Holasterella conferta from the Carboniferous Limestone near 

 Glasgow (' Annals,' 1879, vol. iii. p. 141, pi. xxi. tigs. 1-8), 

 in which the spicules appear to me to come nearest to those 

 of Schmidt's Adriatic species Corticium candelabrum (Spong. 

 Adriat, Meeres, p. 42, Taf. iii. tig. 25) ; but some of the 

 Suberitida might, if fossilized, present a heap of similarly 

 shaped spicules to those of Corticium abyssi (' Annals,' 

 1873, vol. xii. p. 18, pi. i. figs. 1-9 and 15) ; and Cor- 

 ticium Kittoni {ib. 1874, vol. xiv. p. 24, p\. xv. figs. 48 a, 

 b, c) may be equally confounded with the tetrahedral form of 

 a Lithistid, to which perhaps may be added Schulzc's Pla- 



