— 7I — 
Genus Hyalostelia, Zittel. 
(Handbuch der Palaeontologie p. 185). 
Hyalostelia fusiformis n. sp. 
(Plate V, fig. 12—16). 
Free hexactinellid spicules having one axis much longer 
than the others, arms straight or but slightly curved, and 
gradually tapering to a point. The centre of the spicule 
solid and inflated. Very variable in their dimensions. The 
longer axis of the larger spicules is 1,05mm. in length; and 
the central node 0.18 mm in thickness. A small spicule is 
0,45 mm. long; and the central node 0,09 mm. in diameter. These 
spicules are distinguished from the preceding form by the rapid 
tapering of the arms and the prominent inflation of the central 
node. In some examples the arms of the spicule are fusiform, and 
they have the aspect of three robust acerate spicules joined 
together at right angles; in others, the central node is more 
of a spheroidal character and the arms are more distinctly 
marked off from the centre. The smaller spicules are more 
numerous than the larger in the deposit. 
The forms nearest to these spicules are those which have 
been described by Messrs. Young from the Carboniferous strata 
in Scotland under the name of Hyalonema Smithiz, (An. 
Mace Nateidistiio; 45. Viol. 20, p, 425, Fl. XIV), The. bor: 
stead specimens are however much more regular in their form, 
as well as much smaller than the Carboniferous spicules. The 
peculiar fusiform inflation of the central node marks these 
spicules off very clearly from those of any known fossil and 
recent species of this sub-order. 
A spicule approximating in size to the smaller of my 
specimens has been figured by Mr. Carter from the Haldon 
Green sands (An. Mac /N.. A. S: 4, Vol. 7, .p..123,. Pl. VU, 
fig. 15) and he compares it to the silicified fibre of the 
Euplectellidae. A spicule with inflated node but with the 
