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 00021 ". 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. (?). PI. XL, fig. 52. Diameter 0-003" to 

 0-0045". 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 

 00013" to 00017". Near the margin each expands into a small round head, and 

 beyond the line of these heads, the margin is entire. Canaliculi in a disc 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. I 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. Ralfsii, 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 Smith 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 angidaris, n. sp. PI. 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 



