116 BRITISH PALEOZOIC SPONGES. 



belongs to perforate corals like Favosites. In reply to this, Dr. H. Rauff 1 showed 

 more clearly than had been done by previous writers the spicular characters and 

 the structure of the genus, which, however, he placed in the Tetracladina family 

 of Lithistids. Prof. Duncan, 3 still relying on the supposed parasitic borings in 

 the Sponge, has reasserted that it was an originally calcareous organism. What- 

 ever may be the nature of the bodies which Prof. Duncan refers to AlgaB, it is 

 evident, from the fact that they are present in the siliceous matrix of the Sponge, 

 and apparently do not penetrate the spicules themselves, that they have no bearing 

 on the original mineral constitution of the Sponge itself. The specimens, in which 

 the skeleton is now of carbonate of lime, present the same evidence that this mineral 

 is a replacement of silica, as the calcined examples of Astylospongia and other 

 Lithistid Sponges from the Silurian strata, and there is but little doubt that as in 

 these forms the original spicular structure of Hindia was siliceous. 



The character of the spicules, consisting of a central node with diverging rays, 

 and their mode of union to form the skeleton by the clasping of their expanded 

 extremities to the nodes of adjoining spicules, appear to me to indicate their position 

 in the Anomocladina family. 



Hindia makes its first appearance in Ordovician strata in Ayrshire and in 

 Illinois ; it is more abundant in Silurian strata in various places in North America, 

 Russia, Isle of Gothland, Sweden, and in the Drift deposits of Northern Germany. 

 Detached spicules, referable to the genus, are also present in the Carboniferous 

 Limestone of Sligo, Ireland, and the Yoredale Beds of Yorkshire. 



5. Hindia fibrosa, F. Boemer sp. Plate IX, figs. 3, 3 a — 3 e. 



1860. Calamopoba fibeosa, F. Roemer (non Goldfuss). Die silur. Fauna d. 



westl. Term., p. 20, 

 pi. ii, figs. 2, 2 a, b. 



1861. Monticulipoea peteopolitana (in part), F. Boemer. Die fossile Fauna 



von Sadewitz, p. 28. 

 1863. Astylospongia inobnata, Hall. Sixteenth Annual Report State Cabinet 



Nat. Hist., p. 69. 

 1875. SpHiEEOLiTES Nicholsoni, Rinde. Abstract Proc. Geol. Soc, No. 305. 

 1879. Hindia sph^boidalis, Duncan. Ann. and Mag. Nat. Hist., ser. 5, vol. iv, 



p. 84, pi. ix. 

 1883. — fibeosa, Rinde. Cat. Foss. Sponges, p. 57, pi. xiii, figs. 1, 1 a, 1 b. 



1884-5. — — F. Boemer. Lethsea erratica. Palaeontolog. Abhandl., 



2te Bd., Heft 5, p. 310, pi. xxvii, fig. 17. 



Sitzungsber. der niederrhein. Gesellsch. zu Bonn,' 1886. 

 Ann. and Mag. Nat. Hist.,' vol. xxiii (1886), p. 226. 



