502 PROFESSOR GREGORY ON 
Surface marked with strong canaliculi, which are broad near the margin, narrower 
towards the centre, near which they terminate in a portion of the middle of the 
median line; in length about two-fifths of the diameter. At about one-third of the 
radius, or a little more, from the margin, is a strong shade, probably a ridge or 
elevation, of a nearly square outline, placed diagonally to the median line, which 
passes through two of its angles. Half-way from this ridge to the centre is a 
second ridge of a circular form, inclosing the elongated centre, from which the 
canaliculi arise. The radiating canaliculi are fainter within the square ridge, 
stronger outside of it; they diverge as they approach the margin, near which 
their ends are joined by semicircular loops, forming a scalloped inner margin, 
beyond which is an entire outer margin. Diameter about 0-0021’. Canaliculi 
about 40 in a disc of that size. 
This species occurs very sparingly in one of the Loch Fine dredgings, and none 
of those I have seen are larger than the one figured. It is probable, however. 
that it may occur of greater dimensions, as the next species does. 
52. Campylodiscus Ralfsii, Sm. (?). Pl. XL, fig. 52. Diameter 0-005" to 
():0045".. Form orbicular in many instances, but with all the modifications of the 
genus. From two points in the median line, near its extremities, arise two lines, 
diverging in the middle, so as to leave a long, narrow, vacant space, the width of 
which varies from 0:0003” to 0:0005", according to the size of the valve. To these 
lines the canaliculi reach. These canaliculi are narrow, very short near the ends 
of the median line, longest in the middle, where they reach a length of from 
0:0013" to 0:0017". Near the margin each expands into a small round head, and 
beyond the line of these heads, the margin is entire. Canaliculi in a dise such 
as is here figured, 64, curved as they approach the ends, having their concavity 
turned from the centre. The valve is much undulated. 
This fine and conspicuous form first occurred to me in the Glenshira Sand, 
where it is scarce. [afterwards found it, still scarce, in Professor ALLMAN’s Lam- 
lash Bay dredging; and still more recently, I found it frequent in three of the 
Loch Fine dredgings. I have referred it to C. Ralfsii, Sm., although it is so 
much larger than the form figured by him, and although there are other differ- 
ences. Thus in C. fa/fsii, Sm., the canaliculi reach the median line, and the row 
of heads or expansions lie some distance from the margin. But these differences 
cannot be regarded as specific. The smaller variety figured by Smirx occurs also 
in some of the dredgings and in the Glenshira Sand. But the larger form seems 
to be the typical one, and for that reason, chiefly, I have here figured it. 
53. Campylodiscus angularis, n. sp. Pl. XL, fig. 53. Valve orbicular, with the 
usual modifications. Diameter of disc from 0-0025’ to 0-0039", the smaller sizes 
being the most frequent. The canaliculi from 160 to 180 in large examples, 
such as the one here figured. They are very short at the ends of the median line, 
and inclose a broad blank space, which, in the median line, occupies the whole 
