158 BRITISH PALASOZOIC SPONGES. 
Sub-Order.—HExaAcTINELLIDA. 
Growp.—LyYssaKINA. 
Genus.—Hyatostetia, Zittel. 
40, Hyatosrenta Surrat, Young and Young sp. Plate VI, figs. 1, 1 a—1 1, 2, 24 
—2k. 
1876. AcanrHosponera Smiruu, Young and Young. Cat. Western-Scottish 
Fossils, p. 38. 
1876. HyanoneMa PARALLELUM, Young (non M‘Ooy). Ibid., p. 38. 
1877. Acanrwosponera Surruu, Carter. Ann. and Mag. Nat. Hist., ser. 4, 
vol. xx, p. 176. 
1877. HyaLoneMa _— (in part), Young and Young. Ann. and Mag. 
Nat. Hist., vol. xx, p. 426, pl. xiv, 
figs. 1—8, 5—12, 1417; pl. xv, 
fig. 30. 
1877. ACANTHOSPONGIA — Zittel. Studien, Abth. 1, p. 60. 
1878. HyaLoneMA PARALLELA, R. Etheridge, jun. Geol. Mag., new ser., vol. v, 
p- 119. 
1878. — Smirur (in part), Carter. Ann. and Mag. Nat. Hist., ser. 5, 
vol. i, p. 129, pl. ix, figs. 1—9, 
12, 18. 
1878. Hyanosrertra — Zittel. Wandbuch der Pal., vol. i, p. 185. 
1879. HyaLonEMA —  Wicholson. Man. of Pal., vol. i, p. 145. 
1880. — ? Grrvanensp, Wich. and Ether., jun. Mon. Silur. Foss. 
Girvan, Fas. ii, p. 239, pl. xix, figs. 1—1 6. 
1880. AcanrHosponera Smirui, F. Roemer. Lethea Pal., p. 317. 
1883. HyaLosTELIa — Hinde. Cat. Foss. Sponges, p. 150, pl. xxxii, 
figs. 1, la—lg. 
Entire form of Sponge unknown; the portions preserved are fragments of the 
dermal layer with the spicules in situ, detached skeletal-spicules of various forms 
and dimensions, and bundles of elongated, rod-like spicules, and isolated fragments, 
forming the anchoring appendage of the Sponge. 
The dermal layer of the Sponge consists of relatively large hexactinellid 
spicules in which the distal ray of the vertical axis is reduced to a small rounded 
knob or process, or is altogether wanting, whilst the transverse rays are of unusual 
length, end incline downwards from the central node (Pl. VI, fig. 1 a). These 
spicules are disposed so that their transverse rays overlap each other, and thus form 
quadrate interspaces which are partially filled by smaller spicules, whilst the 
