File:The Quarterly journal of the Geological Society of London (12645748165).jpg

1863'..
ROBERTS CRUSTACEAN TRACKS.
233
2. On some Crustacean Tracks from the Old Red Sandstone near
Ludlow. By George E. Roberts, Esq.
.Communicated by the President..
I lately received some sandstone-slabs from the Lower Old Red
Cornstones, obtained by Mr. Alfred Marston, of Ludlow, which ex-
hibit more clearly than is usual tracks and trails of Crustacea. They
were obtained from a somewhat noted quarry at Bouldon, a village
seven miles north of Ludlow. Mr. Marston has furnished me with
the following details of the Bouldon section : —
Eig. 1. — Vertical Section of the Beds exposed at Bouldon Quarry,
near Ludlow.
ft. in.
a. Rough coarse conglomerate ; a few Fish-remains
(Pteraspis, Cephalaspis) 5
b. Fine-grained sandstone with Pteraspides .... 1 3
c. Fvubbly beds 6
d. Fine-grained sandstones with Pteraspides ... 1 6
e. Micaceous sandstones 10
f. Thin-bedded fine sandstone with tracks of Crus-
taceans 4
g. Fine-grained shales 8
h. Lowest Cornstone ; remains of Fish and Crus-
taceans ; Pteraspis and Cephalaspis abundant,
Pterygotus scarce.
A zone of fine-grained and thin-bedded deposits, indicating qui-
escent conditions and shallow water, is thus seen dividing two con-
glomeratic beds, the lower of which I am inclined to regard as the
rock wanting above the plant-bearing bed at Linley, but which is
seen to accompany that deposit at Trimpley, in Worcestershire, and
elsewhere.
The Crustacean tracks occur as casts abundantly upon the under
surface of the thin sandstone-layer, /, of the above section.
Of the three or more varieties, the most important in size and
distinctness (fig. 2) is a slightly curved trail about \\ inch in width,
formed by two series of oval or, rather, flask-shaped prints, \ of an
inch long, each bearing a number of transverse wrinkles parallel
to the direction of the trail. The prints taper inwardly, and have
a slight upward curve at the same end. Their distance from each
other varies, as also does the height of the cast, but these inequali-
ties may be regarded as results of peculiarities of the condition of
the surface which received them.
The indentations made by another Crustacean (?) upon the slabs