LEPTOLEPIS. 121 



Description of Specimens. — All the known examples of this species are much 

 crushed and broken, but it is easily distinguished from the other Purbeckian 

 species by its less elegant proportions and by the serration of the principal 

 flank-scales. Both the head and opercular bones are shown to have been smooth. 

 The vertebral centra are preserved as delicate cylinders, with very little constriction. 

 The fulcra on the anal fin are very slender. The fine oblique serration of the 

 principal flank-scales has already been described and figured by Egerton, who 

 also notes the broad thickened band on the inner face connected with the peg-and- 

 socket articulation (Text-fig. 35c, d, p. 11 -A). There is an occasional opening for 

 slime-apparatus in these scales, but the lateral line as usual clearly passes along 

 the row of small scales immediately below. The dorsal and ventral scales do not 

 appear to be serrated. 



Horizon and Localities. — Purbeck Beds : Hartwell and Bishopstone, Bucking- 

 hamshire. 



Family OligopleuimDjE. 



These are the latest primitive teleosteans which retain fulcra on all the fins. 

 They occur chiefly in the Lower Kimmeridgian (Lithographic Stone) of France 

 and Germany, though they also range through Cretaceous formations. Some 

 Wealden and Purbeck fossils have been wrongly referred to OUgopleurus itself on 

 imperfect evidence (see p. 129), but a maxilla (PI. XVII, fig. 8), from the Middle 

 Purbeck of Swanage, may perhaps belong to the allied genus (Eonoscopus, Costa. 

 This bone much resembles the maxilla of Megalurus and Amiopsis, but it agrees 

 still more closely with the same bone in two specimens of GUonoscopus cyprinoides, 

 from the Lithographic Stone of Bavaria, in the British Museum (as already 

 mentioned in Geol. Mag. [4], vol. ii, 1895, p. 151, pi. vii, fig. 9). It is much laterally 

 compressed, and more than twice as deep behind as in front ; its hinder margin is 

 slightly excavated, while its anterior end is produced into a stout incurved portion 

 for articulation with the palatine. Its outer face is almost smooth, being very faintly 

 rugose, and the oral margin is only slightly sinuous. The teeth do not vary much 

 in size, and are small, but stout and conical, with the blunt enamelled apex turned 

 somewhat inwards. They are hollow and smooth, and closely though irregularly 

 arranged. Some teeth are broken away from the gaps observed in the series. 



Family Leptolepim;. 

 Genus LEPTOLEPIS, Agassiz. 



Leptolepis, L. Agassiz, Neues Jahrb. fur Min., etc., 1832, p. 146. 

 Oxygonius, L. Agassiz, in Brodie's Fossil Insects, 1845, p. 16. 

 Tharsis, C. G. Griebel, Fauna der Vorweli, Fische, 1848, p. 145. 

 Sarginites, 0. Gr. Costa, Atti Accad. Pontan., vol. v, 1850, p. 285. 

 Megastoma, O. G. Costa, loc. cit., 1850, p. 287, 



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