Lower Palaeozoic Rocks of the South of Scotland. 57 
Order COLLODARIA, Haeckel. 
Suborder Beloidea, Haeckel. 
Spumellaria with an imperfect skeleton composed of nume- 
rous solid needles or spicula, scattered irregularly in the 
calymma. (Chalk Rep. pt. i. p. 28.) 
Genus Spelerozoum, Meyen. 
Beloidea socialiaor u Sphaerozoida with branched or radiate 
spicula of one kind.” (Chalk Rep. pt. i. p. 38.) 
Sphcerozoum priscum ) sp. n. (Woodcut, a-f.) 
Under this name I propose to include spicules of various 
dimensions, mostly with four rays, more rarely with only 
three. The rays are usually straight, simple, apparently 
conical, gradually tapering from a common centre to a point. 
Three of the rays are either in a plane or form a low tripod, 
and the fourth ray is nearly vertical to the others. There is 
a close resemblance in form, and approximately in size, of 
these detached spicules to the spicules of recent species of this 
genus and of allied genera of the same group, as shown in the 
4 Challenger ’ Report, pis. ii. and iv. The spicules are very 
abundant, for the most part indiscriminately mingled with 
one another and with the ordinary spherical shells ; some- 
times several are now situated close together, as if resulting 
from the disintegration in position of individual Radiolaria. 
It is very probable that these spicules may represent more 
than one species, and they are grouped under one name simply 
for convenience of reference. In form they are very similar 
to the spicules of Calcisponges ; but there is not the least 
ground for suspecting that they may have belonged to these 
organisms, since their condition of preservation is the same as 
that of the undoubted Radiolarian shells amongst which they 
occur, and they are associated with other spicules which as 
regards form have no counterparts amongst sponge-spicules. 
Detached Radiolarian spicules, both three-rayed and other 
forms, have already been described by Dr. Rust * from the 
Jurassic Strata of Western Switzerland and from the Neo- 
comian of Gardenazza, and they are stated to be abundant 
in all Jurassic Radiolarian-bearing rocks. 
The rays of the spicules range from *04 to T4 millim. in 
length and from *005 to *015 millim. in thickness. 
* ‘ Pakeontographica,’ Bd. xxxi. p. 284, pi. xxxi., Bd. xxxiy. p. 190. 
