18G THE SUCKER FAMILY. 



the base of the caudal extremity of the posterior dorsal. The 

 rest of the body is straw-coloured.' When the dorsal and anal 

 fins are first outlined from the marginal (Agassiz's, Plate IV, 

 fig. 4), he found them ' usually of a bright olive-green, darkest 

 towards the dorsal side, with the same blue band extending 

 towards the operculum from the rear of the orbit, with one or 

 two round blue spots above the level of the pectorals along the 

 lateral line. Other specimens were of a bluish neutral slate 

 tint, uniformly spotted with darker pigment-cells, with the same 

 blue band between the eyes, above the nostrils, and behind the 

 eyes. This was also the colouring of the oldest of the young 

 specimens caught (from 20 to 34 mm.), resembling in general 

 the bluish colouring of the adult, only of a darker tint.' 



' The intermediate stages varied greatly in colouring ; some 

 were of a yellowish-brown, spotted with chocolate-coloured 

 patches, with light greenish bands behind the eyes, and five 

 roundish spots of the same colour along the lateral line, and a 

 similar number of larger spots along the base of the posterior 

 dorsal, extending, in some specimens, along the median dorsal 

 line of the body to the coloured band passing between the 

 eyes. Other stages, with a similar arrangement of elliptical 

 spots of a bluish tint along the dorsal and lateral lines, were 

 of a reddish-brown colour, with pigment-patches of a darker 

 greenish or of a brownish colour, the abdominal region being 

 of a lighter colour.' 



In regard to the coloration of the British examples (Plate 

 VII, fig. 11) some slight differences from the foregoing careful 

 description of the American forms occur. Thus at 12 mm., 

 in June, the general tint is olive-brown with an opalescent 

 bluish bar running from the operculum to the eye, and then 

 forward over the upper lip to the mouth where those of 

 opposite sides almost meet. Traces of the same hue occur 

 on the cheeks and on the pectorals. A cross-bar of the same 

 beautiful tint passes between the eyes, so that the whole forms 

 an A, a pale furrow in front being caused by the premaxillary 

 fold. The effect of these bands in many is heightened by a 

 border of russet-brown. 



Others a little larger, again, have the body dappled with 



