6 



BRITISH FOSSILS. 



respects the resemblance to J. mm is also very remarkable, especially 

 in the form and proportions of the divided nasal, and the turbinal 

 bones, in the position of the orbit, the shortened antero-posterior 

 dimensions of the cranium, the larger size of the teeth, and the 

 absence of the deep pits characteristic of the head bones in Arapaima. 

 The flattened head resembles that of Polypterus, and the scales and 

 operculum those of Lepidosteus. 



To recapitulate the peculiarities of Lophiostoonus : it has the 

 scales of a Ganoid, and the teeth of a Sauroid, associated with 

 characters found in Arapaima and Amia, but differing from all 

 these in outward form and proportions, and in these respects 

 approximating rather to the family of the Godacanths. It would 

 be premature to attempt, from a single specimen, and that an 

 imperfect one, to unsettle established generalizations, without suf- 

 ficient materials to prepare a sound basis of re-adjustment. It 

 is, however, clear that when the period arrives for a re-classification 

 of many genera, both recent and fossil, now occupying somewhat 

 doubtful positions, the subject of this description must form an 

 essential element in the consideration. Cuvier has placed Lepidosteus 

 and Polypterus, Amia and Arapaima, with the Glupeidce ; 

 Agassiz considers the two former as Sauroids, the two latter, 

 Godacanths ; while Miiller places Arapaima with the Glupeidce, 

 and creates a new order, Ganoidei holostei, for the families 

 Lepidosteini and Polypterini, and suggests a third family for the 

 reception of Amia, combined with the fossil genera, Megalurus, 

 Leptolepis, Thrissops, and their allies. This is not the place to 

 enter upon a discussion of the many points raised in such a con- 

 troversy, but we must hope that before long Professor Agassiz, who 

 is now so opportunely located for studying some recent forms im- 

 plicated in the question, may be able to efiect a satisfactory settle- 

 ment of these disputed points. 



History and Geological Position. — The only specimen I have 

 seen of this fish is in the British Museum. It was found in a chalk 

 quarry near Alfriston, in Sussex, and was presented to the National 

 Collection by Captain Beckford, R.N., of Ryde. I am indebted to 

 my friend, Dr. Mantell, for the drawings of the specimen, made 

 some years ago by Mr. Dinkel ; and, in accordance with his wishes, 

 I have named the species after the late Mr. Dixon, a tribute I am 

 too happy to make to the memory of one whose friendship I long 

 enjoyed. 



