FISHES OF THE GENUS ACENTROPHORUS. 



35 



become completely macerated. In the Mavl Slate occasional 

 examples of Palceoniscus freiesleheni may be found in precisely 

 the same drawn-out condition. Unless other specimens exist in 

 which the attenuated form can be shown to be that of tlie living 

 fish the species A. ahbsi should be dropped. 



Acentrophorus glaphi/rus (Agassiz). (Text-fig. 15.) Found in 

 the Mai'l Slate at the base of the Magnesian Limestone, and 



Text-figure 13. 



Sim. ^ ptm. 



rpm. 



mx. ^-^y- 



Acentrophorus alius. Head of Kirkby's type-specimen (Quart. Journ. Geol. Soc. 

 vol. XX. ISBi, pi. 18. fig. 1). About four times natural size, c.liy., ceratobyal ; 

 cl., cleitlirum ; fr., frontal (left side broken away) ; hJiy., lij'pohyal ; l.j., left 

 lower jaw; Z.jom., left premaxilla (part) ; mx., maxilla; j)«., parietals; p.tm., 

 post-temporal; r.^., right lower jaw, inuer surface; r.jpm., right premaxilla ; 

 sq., squamosal ; s.tm., supratemporal ; x., possibly a gular plate. 



therefore the earliest species. More variable in form than 

 A. varians ; some examples, the type-specimen among them, deep 

 in the body, others shallower than the form represented in text- 

 fig. 15. The chief diagnostic character hitherto attributed to the 

 species is a pronounced fine denticulation of the free hinder 

 border of the scales. This denticulation is, however, so very 



3* 



