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Show 346 MR. A. SMITH WOODWARD ON NEW FISHES [Apr. 15, 4. On some new Fishes from the English Wealden and Purbeck Beds, referable to the Genera Oligopleurus, Strobilodus, and Mesodon. By A. SMITH W O O D W A R D, F.Z.S., of the British Museum (Natural History). [Received March 18, 1890.] (Plates XXVIII. & XXIX.) The list of genera and species of Upper Mesozoic fishes met with in the English Purbeck and Wealden beds is already somewhat extensive, many contributions to the subject having been made by Agassiz and Egerton. There still remain, however, several unde-scribed species well represented in collections ; and a few of these in the British Museum, referable to tbe three genera enumerated above, form the subject of the following notes. Researches already published have indicated a close connection between the fish-fauna of the English Purbeck beds and that of the Upper Jurassic Lithographic Stones of France, Bavaria, and Wurtemberg; and the new forms now described tend to demonstrate that alliance even more clearly. The British fossil remains of Oligopleurus are also worthy of special note, apart from questions of distribution ; for their comparatively satisfactory state of preservation adds much to our knowledge of the osteology of this genus, which has hitherto been only imperfectly elucidated. Genus OLIGOPLEURUS. [V. Thiolliere, Poissons Fossiles du Bugey, pt. ii. 1873, p. 21.] OLIGOPLEURUS VECTENSIS, sp. nov. (Plate XXVIII. figs. 1-4, Plate X X I X . figs. 1, 2.) The specimen to be regarded as the type of this species is a large laterally compressed skull and mandible from the Wealden of the Isle of Wight (Brit. Mus. no. 42013), shown, of one half the natural size, in Plate XXVIII. fig. 1. A group of scattered head- and opercular bones, with a series of vertebral centra of an equally large individual, from the same formation and locality (B.M., no. 42014), exhibit some further osteological details. Moreover, the characters of the mandibular symphysis, gill-rakers, and a single vertebral centrum in the first-mentioned fossil show that an imperfect specimen from the Purbeck beds, erroneously determined by Agassiz as Lepidotus minorl, must be assigned to the same form ; and this discovery leads to the identification of other Purbeckian fragments of the axial skeleton, which elucidate additional features of some interest and taxonomic importance. Skull, Mandible, and Opercular Apparatus.---The type specimen is much crushed and broken, but, as shown by the figure (Plate XXVIII. fig. 1), several of the elements are distinguishable and well preserved. 1 Rech. Poiss. Foss. vol. ii. pt. i. (1844). p. 269, pi. xxix. c, fig. 12. |