136 BRITISH PALASOZOIC SPONGES. 
denied its claim to be regarded as a Sponge, and, therefore, proposed for it the 
generic name of Polygonospherites. 
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. SpHmRosPoncia THSSELLATA, Phillips, sp. Plate TV, figs. 2, 2 a—2 d. 
1832 TunicatTE FossiL, Broderip. Trans. Geol. Soc., ser. 2, vol. iii, p. 164, pl. xx, 
figs. 1, 2. 
1841. SpPH®RONITES THSSELLATUS, Phill. Pal. Foss. Devon, &c., p. 135, pl. lix, 
fig. 49. 
1844. = — F. Roemer. Rhein. Uebergangsgeb., p. 64. 
1845. EcnrtnosPHmRitEs — Murch., Keyserl., Vern. Geology of Russia, 
p-. 381, pl. xxvii, 
fig. 7. 
1845. SpHm®RONITES — Bowerbank. Ann. and Mag. Nat. Hist., vol. xv, 
p. 299. 
1845. — — Austin. Idem., p. 406. 
1854. EcnrnospHmRritrs — Morris. Cat. Brit. Foss., p. 79. 
1850-56. Proposcis oF crinorp, G. and F. Sandberger. Verstein. des Rhein. 
Schicht.-Syst., pp. 384, 385. 
1861. SpHmROsPONGIA TESSELLATA, Pengelly. Geologist, vol. iv, p. 340, pl. v. 
1875. Pascronus TESSELLATUS ET Ratut, Kayser. Zeitschr. d. deutsch. geolo- 
gisch. Gesellsch, p. 780, 
pl. xx. 
1880. PoLYyGoNOSPHERITES TESSELLATUS, F. Roemer. Leth. geogn., Th. 1, p. 297, 
fig. 54. 
1880. —_ _— Zittel. Handb. der pal., vol. i, p. 728. 
1883. Dicryopnyron GERoLsTEINENSE, F. Roemer. Zeitschr. d. deutsch. geolo- 
gisch. Gesellsch., p. 706, 
figs. a, b. 
1884. SpHmRosponata TESSELLATA, Hinde. Quart. Journ. Geol. Soc., vol. xl, 
p- 840, pl. xxxvii, figs. 1, la—le. 
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. 
