2 



BRITISH FOSSILS. 



a single row of smooth thick-set villiform teeth. These are well 

 seen in the enlarged representation of a detached head (fig. 2 of the 

 Plate). The pre-operculnm is more nneven superficially than the 

 associated bones, the undulations becoming very strongly marked 

 as they approach the posterior margin, which, however, is not in- 

 cised. The operculum is triangular, the apex directed downwards ; 

 the sub-operculum is nearly as large as the operculum, and both are 

 traversed by indistinct concentric lines of growth. The scales 

 conveying the mucous duct are quadrilateral in the anterior and 

 middle parts of the body, but as they approach the tail the posterior 

 angles are bevelled off, and the long diameter of the scales gradually 

 reduced until they assume the lozenge form. The canal is unusually 

 large, and its course is prominently raised above the surface of the 

 scales. The apertures are for the most part in notches at the poste- 

 rior margins, but occasionally there is, in addition, an orifice in the 

 centre of the scale. The scales immediately below the lateral line 

 are the largest, and are also quadrangular. Tliose below this series, 

 as also those above the lateral line, diminish rapidly in size, and 

 lose at the same rate their angular outline. The surfaces of all the 

 scales are perfectly smooth, and invested with a dense covering of 

 ganoine. The free margins of the larger scales are armed with 

 two or three sharp cusps, but in the smaller scales these are either 

 reduced to a single point or are altogether absent. The fins are 

 mutilated in all the specimens. The pectoral fins appear to have 

 been broad, and to have contained not less than 16 rays. The 

 position of the dorsal fin is rather remote. The ventrals are small, 

 and are placed about the middle of the body ; the anal fin is about 

 the dimensions of the dorsal fin, and is situated nearer to the 

 ventrals than to the tail. The latter fin is not preserved in any of 

 the specimens. 



Locality. — All the specimens yet discovered of this and the two 

 following species of fossil fish, where found by Mr. Higgins in a 

 single block of Gotham marble from the lower lias of Aust Passage 

 There are not less than 14 or 15 individuals all grouped together 

 in a matrix not larger than the plate which accompanies this 

 description. Owing to the liberality of the discoverer, specimens 

 of this species are in the collections of the Bristol Institute, the 

 Rev. P. B. Brodie, the Earl of Enniskillen, and my own ; and I am 

 indebted to him and the other possessors for the loan of their 

 (specimens for the purpose of comparison and description. 



