A HISTORY OF SUSSEX the sharp-toothed sharks of the extinct genus Oxyrhina, one species, O. mantelli, was described by Agassiz from Lewes specimens ; two other species, O. angustidens and O. crassuletis, also occur in the Chalk of the county, remains of the latter (including a fine associated series of teeth and vertebrae in the Brighton Museum) having been obtained from Lewes, Houghton and Arundel. The porbeagle-sharks are represented by La??jna appendiculata from Lewes and Arundel, and L. sulcata from Lewes. Another shark, Corax falcatiis, belonging to an extinct genus nearly allied to Carcharodon, but with smaller teeth, was named by Agassiz on the evidence of specimens collected by Mantell in Sussex. Passing on to the chimaeroid fishes, whose dentition takes the form of large triturating plates on the jaws, we find certain Sussex specimens identified with a species provisionally assigned to the Jurassic genus Ischyodus under the name of /. incisus. Of the allied Cretaceous genus Edaphodon four or five species are known to occur in the Chalk of the county, namely E. sedgwicki, E. mantelli (from Arundel, Brighton, Clayton, Glynde, Houghton and Lewes), E. agassizi (from Hamsey and Lewes), and E. crassiis. A tooth from Glynde may possibly belong to E. reedi. The second and third of these were named from Sussex specimens, A fifth species, based on specimens in the Brighton Museum, was described in 1878 by Mr. E. T. Newton, but was subsequently made the type of a distinct genus, under the name of Elasmodectes willetti. The Brighton specimen, we believe, still remains the unique example of this fish. A fish-spine from the Sussex Chalk described under the name of Ccelorhynchus cretaceus may, as in the case of the Bracklesham specimen with the same generic title, prove to belong to one of the sharks or chimsroids described upon the evidence of the teeth. A fish from the Lewes Chalk described by Agassiz as Macropoma mantelli is of considerable interest as one of the comparatively few repre- sentatives in the later strata of the group of fringe-finned ganoids, which were so abundant in the Paleozoic, and of which the African bishir is the sole surviving member. The Sussex species is the only repre- sentative of its genus ; its remains occur at North Stoke near Arundel, Lewes and elsewhere. Of the pycnodont ganoids, already briefly men- tioned under the heading of the Bracklesham beds, the species Gyrodus cretaceus was described by Agassiz from Lewes specimens. Some im- perfect remains of the group have been described as Microdus occidentalis, but their affinity is doubtful. The species Ccelodus parallelus {Pycnodus of Dixon) is however a good one, of which the only known example is in the Brighton Museum. Another genus of pycnodonts is represented in the Sussex Chalk by Anomaodus angustus from Houghton, Lewes and Newtimber, and A. ivillctti from Glynde. The former was described by Agassiz (as Gyrodus) from a Lewes specimen, and the latter by Dr. Smith Woodward from the unique example in the Brighton Museum. Certain other pycnodont remains from the Chalk of the county are of uncertain affinity ; one type has been identified with the so-called Pycnodus scrobiculatus, first described from the continent ; the second 32
