TRANSACTIONS OF THE SECTIONS. G5 



dance of minute Crustaceans belonging to the same group with the Cypris, a small, 

 bivalvular, pencil-footed animal, abounding in shallows of fresh water, where the 

 warmth of the sun and abundance of decaj'ing vegetable and animal matter conduce 

 to their rapid multiplication. Beside these, there is a marine group called Cythera, 

 and it is not easy to determine to which of these groups the fossil species belong ; and 

 in consequence the marine or fluviatile origin of the strata in which they occur is not 

 always safely determinable from their occurrence. In the Weald of Sussex, and in 

 the tertiary beds, their identification with the freshwater group is probably correct ; 

 but they occur also in situations not hitherto expected, and where the evidence re- 

 mains to be examined. In the coal-shales of Yorkshire, which are 4000 feet thick, 

 there occurs a band of marine shells, such as Goniatites, Orthoceras, and Pectens, 

 without one freshwater shell, and above and below it, beds with indications, by shells, 

 of fluviatile, if not decidedly freshwater origin ; and the author noticed in 1831, that 

 Cyprides occur mixed with the freshwater shells above the marine deposit. Dr. Hib- 

 bert described in 1834, to the British Association at Edinburgh, what he conceived to 

 be freshwater Cyprides in the limestones of Bardie House ; and in 1836 Mr. Phillips 

 discovered vast abundance of Cyprides in the limestone of the upper coal-measures at 

 Ardwick, north of Manchester, and immense numbers in black shales of the Bradford 

 Collieries; and Mr. Binney has since found them in a great variety of situations. 

 To the Dublin Geological Society (1840) Mr. M'Coy has announced thirteen or four- 

 teen species in the mountain limestones of Kildare, which are full of marine organic 

 remains. Mr, Phillips had lately observed in Pembrokeshire, in the lowest shales of 

 the mountain limestone, within ten feet of the old red sandstone, beds of Cyprides 

 very similar to those in the black shales of the upper coal-measures in Manchester. 

 These are probably the most ancient specimens of the group yet discovered. The 

 circumstances under which these Crustaceans are found at the present day appear to 

 agree with those attending their occurrence in a fossil state ; the recent Cyprides 

 seem destined to consume the perishing parts of animal and vegetable substances ; 

 and the fossil species are generally associated with portions of fishes near Manchester, 

 as observed at Ardwick by the author, and elsewhere by Mr. Binney, and by Dr. 

 Hibbert at Burdie House. In Caldey Island they are in like manner associated with 

 bone- and fish-beds. Probably their remains occur under many circumstances ; but 

 to ascertain all the conditions under which they lived, requires attention to many 

 sorts of strata not often suspected to contain remains. Very remarkable conditions 

 occurred when the old red sandstone ceased to be deposited ; for then, after a long 

 series of formations vvith no trace of organic remains, we find in the beds imme- 

 diately above thousands of minute Crustaceans, bone-beds, layers of Brachiopoda, &c., 

 of marine origin ; and, encouraged by this example, we may expect to find them in 

 beds of still higher antiquity. 



Mr. J. Phillips remarked the fact of these cypridiform Crustaceans constituting the 

 general type of Enfomosfraca through a large range of the strata, being in the older 

 or palaeozoic rocks unaccompanied by decapodous Crustaceans, which lie in later de- 

 posits, but flanked by a parallel series of Trilobites, which are absent from those 

 newer strata, 



On the genus Cardinia, Agassiz, as characteristic of the Lias Formation. 

 By H. E. Strickland, F.G.S. 



Mr. Strickland called attention to a genus of bivalve Mollusca which is peculiarly 

 characteristic of the Liassic series. This genus, wliich was named Cardinia by M. 

 Agassiz in the ' Etudes critiques sur les Mollusques fossiles,' has also been termed 

 Pachyodon by Mr. Stutchbury, and Ginorga by Mr. J. E. Gray. It appears to belong 

 to the Venerida, and in external form approaches Pnllastra, but is distinguished by 

 possessing, in addition to the converging cardinal teeth, a pair of very strong lateral 

 ones analogous to those of Cardium. From the ovate form of the shell and the struc- 

 ture of the hinge, the species of this genus have been referred by most authors to the 

 Unionidce, but are sufficiently distinguished \ty the lunule beneath the umbo, and by 

 their marine habitat, as proved by the other fossils found in company with them. 

 Ten or t\^elve species are known of this genus, the whole of which occur either in 

 the marlstone or the lower lias. Seven of these species were exhibited; but as it was 

 understood that Mr. Stutchbury proposed publishing a monograph of the genus, 



1841 " F 



