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 Woodward, 

 F.Z.S., of the British Museum (Natural Histoiy) . 



[Received March 18, 1890.] 



(Plates XXVIII. & XXIX.) 



The list of genera and species of Upper Mesozoic fishes met with 

 in the English Parbeek 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, referaljle to the 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 Litho- 

 graphic 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 com- 

 paratively satisfactory state of preservation adds much to our know- 

 ledge 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 XXIX. 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 speci- 

 men from the Purbeck beds, erroneously determined by Agassiz as 

 Lepidotus minor ^, 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. 



' Kech. Poiss. Foss. vol. ii. pt. i. (1844). p. 2(ilS pi. xxix. c. fig. V2. 



