120 BRITISH PALAEOZOIC SPONGES. 



to me sufficient to justify placing them with Sponges notwithstanding the abnormal 

 character of the spicules and their peculiar arrangement in the skeleton. 



Ischadites makes its first appearance in Ordovician strata (Llandeilo), and 

 continues through the Silurian, but has not been recognised above this horizon. 

 It occurs in Wales and the West of England, Scotland, Norway, Isle of Gothland, 

 Sweden, Baltic Provinces of Russia, and in the United States and Canada. 



7. Ischadites Kcenigii, Murchison. Plate II, figs. 1, 1 a, 1 b. 



1839. Ischadites Kcenigii, Murchison. Silurian System, p. 697, pi. xxvi, 



fig. 11. 

 1837. Polypaeium — Hisinger. Lethsea Suecica, p. 115, pi. xxxvi, Supple- 



ment, fig. 2. 

 1842. Eeceptaculites Beonnii, Eichwald. Urwelt Eusslands, Heft 2, p. 80, 



pi. i, fig. 9. 

 1852. Selenoides iowensis, B. Dale Owen. Geol. Surv. Wisconsin, Sua., p. 587, 



pi. ii b, fig. 13. 

 1854. Receptaculites Neptuni, Morris. Cat. Brit. Foss., 2nd edit., p. 363. 

 1858. — Eicuwaldi, Schmidt. Die Silur. Formation von Ehstland, 



&c, p. 232. 

 1860. — Beonnii, Eichwald. Lethaea rossica, vol. i, p. 429, pi. xxvii, 



figs. 2 a, b. 

 1860. Ischadites Eichwaldt, Eichwald. Lethaaa rossica, vol. i, p. 436, pi. xxvii, 



figs. 3 a, b, c. 

 1865. Eeceptaculites Jonesi, Billings. Pal. Foss. Canada, vol. i, p. 385, fig. 



363 ; p. 389, fig. 365. 



1865. — igwensis, Billings. Ibid., p. 385, fig. 364. 



1866. Ischadites antiquus, Salter. Mem. Geol. Surv. Gt. Brit., vol. iii, p. 282, 



fig. 4. 



1867. — tessellatus, Salter, MS. (See Siluria, 4th ed., p. 509.) 



1868. Eeceptaculites globulabis, Meek and Worthen. Geol. Surv. Illinois, 



vol. iii, p. 301, pi. ii, 

 figs. 2 a, b. 

 1868. — sp. ? - — Ibid., p. 301, pi. ii, 



figs. 1 a, b. 

 1873. Ischadites Kosnigii, Salter. Cat. Cambrian and Silur. Foss. Cambridge, 



p. 100. 

 1875. Eeceptaculites OniOENsis, Hall and Whitfield. Geol. Surv. Ohio, Pal., 



vol. ii, p. 123, pi. vi, 

 fig. 1. 

 1875. — subturbinatus, Hall. Twenty-Seventh Annual Eeport 



State Museum, Albany, pi. iii, 

 figs. 1, 2, 3. 



