HYALOSTELIA. 161 
41, Hyatosrenia paraiena, M‘Ooy sp. Plate VI, figs. 3, 3 a—3 g. 
1844, SERPULA PARALLELA, U‘Coy. Synop. Carb. Foss. Ireland, p. 169, pl. xxiii, 
fig. 30. 
1843. — soctaLis, Portlock (non Goldfuss). Geol. Report Londonderry, 
p- 862, pl. xxva, figs. 
9a, 96. 
1854. — PARALLELA, Morris. Cat. Brit. Foss., p. 92. 
1866. HyanonrMa PAaraLLeLum, Swess. Ann. and Mag. Nat. Hist., ser. 3, vol. 
xvili, p. 404. 
1878. — Younar?, R. Etheridge, jun. Geol. Mag., vol. v, p. 119. 
1880. AcESTRA PARALLELA, F. Roemer. Lethea Pal., p. 318, fig. 60. 
1880. SaRcoHEXACTINELLID, Carter. Ann. and Mag. Nat. Hist., ser. 5, vol. vi, 
p- 211, pl. xiv 8, figs. 8, 9. 
1881. AcESTRA PARALLELA, Nathorst. Omspir af nagra evertebrade djtr., Kong. 
Svenska. vetensk. Akad. Handl., Bd. 18, 
No. 7, p. 46. 
1883. Hyatostrerra — Hinde, Cat. Foss. Sponges, p. 151. 
This species includes simple and modified hexactinellid spicules, probably 
belonging to the body-skeleton and the dermal layer, together with fragments of 
the spicular bundles, and detached rod-like spicules, forming the anchoring appen- 
dages of the Sponge. Inthe spicules of the dermal layer only five rays are present, 
the distal ray not being developed. The transverse rays are straight or slightly 
curved, nearly cylindrical, or but slightly tapering, and terminate obtusely. The 
rays vary from ‘45 to 1°5 mm. in length, and from ‘1 to ‘25 in thickness. The 
spicules are siliceous, and in some specimens the canals are preserved. 
The elongated spicular rods of the anchoring-rope of the Sponge have smooth, 
even surfaces, and appear to be cylindrical. Near the distal ends they slightly 
expand, and they terminate in conical extremities with four short, stout, recurved 
points or rays. The canals in these spicular rods are usually preserved, and in 
some instances the concentric layers can be seen (PI. VI, fig. 3 f). As a rule they 
are now of chalcedonie silica, but in some cases the silica has been replaced by 
calcite. The anchoring-spicules sometimes occur detached from each other, and 
widely spread out on the surface of the rock; not unfrequently they are grouped 
into compressed bundles of 5 to 9 mm. in width, in which the component spicules 
are nearly in contact and disposed parallel to each other. Fragments of these 
bundles or ropes occur, having a length of 140 mm. The individual rods in the 
same bundle exhibit considerable variation in size; they range from ‘05 to °5 mm. 
in thickness. 
This species was originally proposed by Portlock for narrow bands or bundles of 
