Genus Gyracanthus, Agassiz. 47 
description is correct *, G. nobilis is even more distinct from 
G. alnwicensis than from any other. 
One remarkable feature in these spines as occurring at 
Borough Lee is the small amount of apical wearing to which 
they have for the most part been subjected. Hven the extreme 
point, only a little blunted and polished, is sometimes present 
in large specimens, and in many others comparatively little of 
the extremity has been lost by that process which has reduced 
some of the large Gyracanthus-spines from Northumberland 
and Staffordshire to mere stumps. It has been noted that 
this wearing process has obliquely truncated the Northumbrian 
specimens in their anterior aspect ; but in those from Borough 
Lee evidence of wearing is sometimes found on the posterior 
aspect as well. These circumstances would lead us to infer 
some difference either in the habitat or the habits of the species 
in question. 
Gyracanthus Youngit, Traq. 
Gyracanthus Youngit, Traq. Geol. Mag. dee. ii, vol. x. 1885, p, 543. 
Occurring also at Borough Lee, but found likewise in many 
other localities on the horizon of the Scottish ‘ Edge”? Coal 
or Middle Carboniferous Limestone series, is a remarkably 
distinct species of Gyracanthus, to which T have given the 
name C. Youngii, in honour of my friend Mr. John Young, 
of the Hunterian Museum, Glasgow, who has done so much 
for the elucidation of the paleontology of the west of Scotland. 
The finest specimens I have seen are in the collection of Mr. 
R. Craig, Beith, Ayrshire, and are from the shale overlying 
the Clay-band Ironstone at Barkip, Dalry. I have also seen 
specimens from Bo’ness in Linlithgowshire (collection of 
Mr. H. M. Cadell), Possil in Lanarkshire (collection of Mr. 
John Young), Cowdenbeath in Fife, and Maryhill near 
Glasgow. 
These are large spines, some of ‘which must have attained 
a length of over 2 feet, had not their apices been worn off. 
They always show some amount of lateral curvature ; but the 
degree to which they are antero-posteriorly bent is very 
* Possibly it is not, as Agassiz never saw the specimen, but drew up 
his description from a drawing sent to him by Messrs. Buckland and De 
la Beche. As reproduced in the plate in the ‘ Poissons fossiles,’ this 
drawing looks like a very hurriedly executed pen-and-ink sketch, from 
which it is quite impossible to identify any thing. Under these cireum- 
stances doubt whether the term “ alzwicensis” has any more value than 
a mere manuscript name. 
