172 BRITISH PALAOZOIC SPONGES. 
which serve as notches, in which adjoining rays are held in position. In addition 
to the normal-umbrella spicules there are anomalous forms consisting of five or six 
unequal rays diverging irregularly from a common centre. In these it is difficult 
to recognise either the shaft or the transverse rays of the normal spicules. The 
spicules are irregularly intermingled together, the smaller forms in the interspaces 
between the larger. At their points of contact the rays are frequently firmly 
fused together; this fusion is evidently of natural origin, and not produced by 
secondary fossilization. The connected skeleton is thus of an intricate, confused 
character, in which it is not always easy to trace the individual spicules. 
In a large spicule a single ray is 4°6 mm. in length, and 1:3 mm. in thickness 
at its base ; the rays of smaller forms are about 1 mm. in length. 
This species is based on a fragment of the connected skeleton, in which the 
spicules retain their original arrangement, as well as on detached spicules. It is 
characterised by the relatively large size and the irregular development of the 
spicules. The dermal layer is not yet known. The form appears to be rare, and 
limited in its distribution. 
Distribution.—Carboniferous. Lower part of Lower-Limestone series, Craw- 
field Quarry, Beith, Ayrshire (J. Young). 
Genus.—ASTERACTINELLA.'—Hinde, gen. nov. 
Syn.—Holasterella (in part), Carter, Hinde. Hyalonema (in part), Young and 
Young. 
Form of entire Sponge unknown, the skeleton consists of relatively large 
spicules, in which a variable number of unequal rays radiate from a common centre 
in different directions. The simplest form of these spicules has a principal vertical 
axis, and from six to fourteen rays diverging from the centre at varying angles. 
In another form one ray is conspicuously larger than the others, which radiate 
star-like from its summit. In others the rays are subequal. The most complex 
form consists of a number of rays extending from a common centre in a generally 
horizontal direction ; the proximal portion of these rays coalesces together, so that 
the upper surface of the spicule has the appearance of the extended corolla of a 
flower, whilst beneath this are three or four robust divergent rays (Pl. VIII, 
figs. 3.e, 3f). Smaller spicules in which numerous simple blunt rays diverge from 
a centre also probably belong to this genus. These various forms of spicules 
appear to have been irregularly intermingled together to form the skeleton. A 
few fragments have been found in which the rays of adjoining spicules are now 
1 dorijp, star; axriv, ray, dimin. 
