BRITISH FOSSILS. 



Decade VI. Plates X., X*. 



LOPHIOSTOMUS DIXONI. 



[Genus LOPHIOSTOMUS (Xocpios, lophius, o-Toixa, os). Egerton. (Sub-kingdom 

 Vertebrata. Class Pisces. Order Goniolepidoti. Family Sauroidei. Sub-family Sau- 

 roidei homocerci.) Body short and thick ; head depressed ; mouth large, dehiscent ; 

 premaxillary and maxillaries with a single row of large, conical, incurved, grooved teeth ; 

 smaller teeth on the vomer and palatines ; divided nasal ; lower jaw deep, with an outer 

 row of stronger and an inner row of weaker teeth ; glossohyal expanded into a broad 

 plate; scales rhomboidal, ganoid, pitted on the surface and serrated at the posterior 

 margin.] 



Species unica. — Lophiostomus Dixoni, Egerton. 



Descriiotion. — In order to convey an adequate idea of this singular 

 fisli, it has been necessary to exceed the limits of illustration generally 

 adopted in this publication. The two plates, from the masterly 

 hand of Mr. Dinkel, contain four views of the specimen, together 

 with magnified representations of the scales and teeth. The num- 

 bers used to designate the various bones are those employed by 

 Professor Owen, in his writings on the homologies of the Vertebrate 

 skeleton. It is not in this respect only that I am indebted to my 

 distinguished friend ; I have also to acknowledge the invaluable as- 

 sistance he has afforded me in working out the details of this curious 

 fossil, and his recognition of its affinities to the recent Arcqoaima. 

 In form this fish was short, squat, and bulky, contrasting remark- 

 ably in these respects with the more or less elongated features of the 

 abdominal predatory fishes, both recent and fossil, and recalling 

 rather the similitude of a Siluroid. The head is wide and flat- 

 tened, and measured probably more than a fourth of the entire 

 length. The muzzle is broad and semicircular, projecting somewhat 

 beyond the lower jaw ; the gill-covers are large, and the branchi- 

 ostegous rays of great strength. All these bones are invested with a 

 dense layer of ganoine, having the surface raised into innumerable 

 small prominences more or less confluent or distinct, resembling in 

 this respect some recent Siluroids and fossil Ganoids. The frontal 

 bones (Plate x*, fig. 11) form a large, somewhat triangular plate, 



[VL X. X* ] 6 L 



