136 BRITISH PALAEOZOIC SPONGES. 



denied its claim to be regarded as a Sponge, and, therefore, proposed for it the 

 generic name of Polygonosphcerites. 



This genus is distinguished from other members of the family by its form, by 

 the regular hexagonal figure of the spicular plates, and by the absence of entering 

 spicular rays. 



The genus appears to be limited to Devonian strata ; it has been met with in 

 Devonshire, in Germany, and in Russia. 



16. Sph^irospongia tessellata, Phillips, sp. Plate IV, figs. 2, 2 a — 2 d. 



1832 Tunicate fossil, Broderip. Trans. Geol. Soc, ser. 2, vol. iii, p. 164, pi. xx, 



figs. 1, 2. 

 1841. Sphjeronites tessellatus, Phill. Pal. Fobs. Devon, &c, p. 135, pi. lix, 



fig. 49. 



1844. — — F. Boerner. Ehein. TJebergangsgeb., p. 64. 



1845. EcMNOSPHiERiTES — Murch., Keyserl., Vern. Geology of Russia, 



p. 381, pi. xxvii, 

 fig. 7. 

 1845. SphjEronites — Bowerbank. Ann. and Mag. Nat. Hist., vol. xv, 



p. 299. 

 1845. — — Austin. Idem., p. 406. 



1854. EcniNOSPHiERiTES — Morris. Cat. Brit. Foss., p. 79. 



1850-56. Proboscis of crinoid, O. and F. Sandberger. Verstein. des Rhein. 



Schicht.-Syst., pp. 384, 385. 

 1861. Spujerospongia tessellata, Pengelly. Geologist, vol. iv, p. 340, pi. v. 

 1875. Pasceolus tessellatus et Rathi, Kayser. Zeitschr. d. deutsch. geolo- 



gisch. Gesellsch, p. 780, 

 pi. xx. 

 1880. Polygonosphterites tessellatus, F. Boerner. Leth. geogn.,Th. l,p. 297, 



fig. 54. 

 1880. — — Zittel. Handb. der pal., vol. i, p. 728. 



1883. Dictyophyton Gerolsteinense, F. Boerner. Zeitschr. d. deutsch. geolo- 



gisch. Gesellsch., p. 706, 

 figs, a, b. 



1884. Sph-Erospongia tessellata, Hinde. Quart. Journ. Geol. Soc, vol. xl, 



p. 840, pi. xxxvii, figs. 1, 1 a — 1 c. 



The examples of this species show many gradations of form between open cup- 

 shaped and pyriform, and they are equally as variable in size. The type specimen, 

 though imperfect, is 85 mm. in height and 115 mm. in width near the summit. 

 The average height of a number of examples in the British Museum is 60 mm., 

 and they are nearly of the same width. 



