BRITISH FOSSILS. 



3 



between tlie ventral and caudal fins. The latter organ is sym- 

 metrical ; it has eight rays in the upper lobe, springing from the 

 terminal vertebra, and three or four marginal rays above. The 

 lower lobe has from eight to ten rays. The scales are small and 

 very thin, finely sculptured with delicate, concentric strise on the 

 enamelled surface. This species differs from the following in its 

 more elongated proportions and the relative small size of the head, 

 as well as in the form of the centrum of the vertebrae. 



Affinities. — The generic relations of Leptolejns Sive with Thrissops 

 and Megalurus. Professor Miiller considers the recent Aonia to be 

 a living representative of this section of the Ganoid order, and pro- 

 poses to group them as a family of his Ganoidei holostei. The 

 affinities of the species have been alluded to in the description. 



Locality and Geological Position. — This fish appears not un- 

 common in the Oxford clay, at Christian Malford, associated with 

 several other species of fossil fish, and with the cephalopodal remains 

 so remarkable for the rare conservation of their more perishable 

 parts. 



Explanation of Plate. 



Fig. 1. Fish, the size of nature, a. coronoid process. 6. premaxillary. 

 Fig. 2. Specimen with the mouth open. a. coronoid process, b. premaxiUary. 

 Fig. 3. Specimen shov/ing the under part of the head. a. a. coronoid processes. 

 Fig. 4. Scales, magnified. 



P. DE M. Grey Egerton. 



