sinus or place of the notch, and without any dorsal furrow. Such carapaces are not rare in some Lower Carboniferous strata. 1. Polycope Burrovii is subglobular, from Settle. 2. P. simplex, oval, obliquely truncated at the antero-ventral edge, is common at Cork and Duleek, Ireland ; and Dr. Rankin found seventeen in one iron- stone nodule from Braidwood, near Carluke. It is somewhat like Cypridina primceva ; but the want of the notch and beak is its cha- racteristic difference. 3. P. Youngiana, from the Lower Lime- stone of Campsie, near Glasgow, is oval and slightly pinched-in or indented on the antero-ventral quarter, and has a striolate ornament.
This genus is the last described in tbat portion of the Monograph which is now completed. Cytherella, belonging to an allied group, is known to occur in the Mountain Limestone ; and Leperditia, Beyrichia, Kirkbya, Moorea, and Entomis, all palaeozoic genera, abound ; forms referable probably to Cythere, Cypris, Candona, &c. are also known in the Carboniferous formations.
Discussion.
Mr. Gwyn Jeffreys inquired as to the greatest depth at which recent marine Entomostraca had occurred. So far as he knew, they were abundant in the Littoral and Laminarian zones, and very scarce in the Coralline. He was not aware of their occurrence at a great depth.
Prof. T. Rupert Jones stated that in the Carboniferous limestone the Cypridinidse frequently occur in layers, but he thought these were deposited at no great depth, probably not more than 100 fathoms. The greatest depth from which he had seen Entomostraca from the Atlantic was upwards of 1000 fathoms. These, however, belonged to different genera from those which he had been describing. Their modern congeners, though mounting to the surface in the evening, no doubt descended to considerable depths during the day.
May 14, 1873.
The following communications were read : —
1. On the genus Palaeocoryne, Duncan & Jenkins, and its Affinities. By P. Martin Duncan, M.B. Lond., F.R.S., V.P.G.S., Professor of Geology in King's College, London.
[Plate XIV.]
Five years have elapsed since I completed the description of a very interesting fossil from the lower Carboniferous shales of Ayrshire and Lanarkshire, with the assistance of Mr. H. M. Jenkins, F.G.S.
The results of our labours were read before the Royal Society on June 17, 1869, and were subsequently published in the Philosophical Transactions, vol. clix. p. 693 (1869), under the title of " On Paloeo-
