148 THE ARMED BULL-HEAD FAMILY. 



chief coloration is fine chrome yellow with black, especially on 

 the breast-fins, spines and dorsal-fins. In the breast-fins the 

 yellow pigment follows the line of the rays, with black points 

 here and there, the intermediate regions being yellow and black. 



Some a little older reach 19 mm. towards the end of May, 

 and are stouter and hardier fishes with a greater development 

 of dark pigment on the dorsum, while three deep brown bands, 

 separated by pale bars, occur on this region of the slender 

 body. The cephalic ridges are prominent and the anterior 

 dorsal spines are large and powerful. The papillse under the 

 chin show little change. In specimens of this length (19 mm.), 

 with the huge fan-shaped breast-fins, obtained from the tow- 

 nets in the open water offshore, in the midst of a vast 

 assemblage of the pelagic stages of other fishes, the spines 

 are remarkably acute all over. Ou the other hand, examples 

 of the same length, captured (jn the bottom within the estuary 

 of the Forth, already have blunt spines throughout, the 

 cephalic ridges flattened and the general aspect more closely 

 like that of the adult, especially in regard to the dense greyish 

 pigment on the upper surface. The breast-fins, however, are 

 much larger, but the ' cilia ' beneath the chin are short. The 

 black bar on the second dorsal, and on the anal fin, is very 

 distinct, while in spirit the first dorsal is pale. 



The young armed bull-heads reach 25 to 26 mm. at the 

 end of June and beginning of July, and the pigment-bars of 

 the body are distinct. The ventral fins are more elongated. 

 The dorsals are variegated with black pigment (in spirit) and 

 the bar still occurs in the anal. The tail-fin is likewise 

 variegated. The authors of the Scandiitavian Fishes observe 

 that Kroyer thought the young reached 90 to 100 mm. in 

 September, but the captures hitherto made in this country 

 do not seem to corroborate this opinion. It is more likely 

 that the specimen of 32 mm. in the Royal Museum at Stock- 

 holm was a large example of that season, just as that of 50 mm. 

 in December would be an older form of the same series. Those 

 procured by Ekstrom in spring on the coast of Bohuslan, and 

 measuring 80 to 100 mm., were probably a year and some 

 months old. 



