CRUSTACEA AND ARACHNIDA OF THE CARBONIFEROUS ROCKS. 521 
spine-like embossing arranged in its long direction. The filaments, which are 
hollow and depressed, have a central plain portion bounded by a raised margin. 
In addition to this the external edges are serrated with a miniature pattern to 
that on the limbs. On the internal margin only a few denticles are shown 
near the tips. On an average eight filaments are given off on each side in a 
distance of 10 mm., so that a comb 17°5 cm. long would support 280 filaments. 
In the above specimens the test has been well preserved. It is horny, tough, 
and elastic, black and opaque where thick, and rich brown and translucent 
where thin. The rachis in the case of the Lennel Braes specimens is flattened, 
and conforms to the bedding planes of the stone in which it occurs ; but in that 
from Cockburnspath the “ Cycadites,” being embedded in sandstone, it is pre- 
served in the round. In it the greater portion is broken away, but there is still 
a part preserved near the tip, which shows a cross section pyriform in shape, 
with the broader end downwards, measuring in depth 4°5 mm. and 3 mm. in 
breadth at its widest end. From this fact it would appear that the comb could 
not have been hid under an opercular plate, but must have been an external 
organ. The rachis of this specimen also shows that as well as the downward 
curve noticed in the Lennel Braes ones, that there was a gentle curving in- 
wards especially near the extremity, just as in the combs of recent scor- 
pions, thus giving us a very good indication of the amount of rotundity or 
depression of the body of the animal to which it must have conformed itself 
(see fig. 18). 
The specimens again throw light upon the apparent narrowing of the 
leaflets of the Cycadites Caledonicus at their bases, as described by SALTER 
in the Survey Memoirs. The filaments, which are at first set on obliquely to 
the rachis, soon bend round so as to lie almost in the same plane as itself, thus 
giving rise to the deceptive appearance which doubtless misled him. 
Horizon.—Calciferous Sandstone Series. 
Disyecta Membra of Glyptoscorpius. 
Combs.—A portion of a comb similar to those described, though much 
smaller and differing in ornament from them, was obtained from the Cement- 
stone Shales at Tarrasfoot, near Langholm. A portion of the rachis, 1:5 cm. 
long by 5 mm. broad, with about thirteen filaments, the longest of which 
measures about 1°8 cm., is still seen. These latter are arranged exactly as in the 
former case, but the serrations on the outer margins of the filaments are much 
longer in proportion than in G. Caledonicus. The rachis is also much thicker 
in proportion to the filaments (figs. 20 and 20a). 
Horizon.—Calciferous Sandstone Series. 
Collector—A. MAcconoculE. 
