On the Geology of Moffat, Dumfriesshire. 383 
are most hooked towards the ends of the rays. There is 
however, a peculiar feature to be noticed in this species : 
although it has not the jaw-like spine, it is furnished with 
" two little obsolete or undeveloped spines/' Ophiocoma 
rosula and Ophiocoma hellis have one only of these " obsolete 
spines" — valves I would rather call them — for an opening 
may be seen when these are raised, out of which the pin- 
nated cirrhi are protruded. I regret exceedingly that I can- 
not find the drawings of Ophiocoma rosula where these cirrhi 
are shown, and which I sketched from a living specimen. 
I find in a specimen of Ophiocoma Ballii that the lowest 
spines on the under side of the rays are crowned with small 
hooks ; and I have every reason to believe that most of the 
Ophiocoma are more or less provided with hooks, either on 
straight or jaw-like spines. 
Description OF Plate XX. 
Fig. 1.— Part of a ray of Ophiocoma hellis, showing spines, valves, &c. 
Figs, 2, 3, 4, 5, 6, 7, 8.-— Spines from various parts of the ray. 
Fig. 9. — Part of a ray of Ophiocoma granulata, showing spines, &c. 
Fig. 10.— One of the uppermost spines. 
Fig. 11. — Hooked spine from the under side of the tip of a ray. 
VII, The Geology of Moffat, Dumfriesshire. By William 
Carruthers, Esq., F.L.S. 
Lithology. 
I purpose in this paper describing the geological features of 
the district around Moffat, taking the village as my centre, 
and including all that lies within a radius of four or five miles. 
The district is situated in the centre of the immense Silurian 
tract of the south of Scotland ; its predominant rocks conse- 
quently belong to the Silurian period. A red sandstone lying 
unconformable to them is the only other stratified rock. The 
superficial deposits are not numerous ; they consist of boulder 
clay, gravel and sand, peat and shingle. A trap-dyke, which 
runs through the district a mile below Mofikt in a south-east 
direction, is the only igneous rock with which I am ac- 
quainted. 
VOL. II, 3 D 
