THE MILLER'S THUMB 75 



There are two or more marine species of Cottus found on 

 the British coasts, but there is only one fresh-water species in 

 ^, ,, „ , Europe, although two well-defined and constant 



The Miller's .. ° ,„. ... -ij 



Thumb varieties occur on the Continent, distinguished as 

 ^ "^ ^°^^°'^' microstomus 3.nd ferrugineus. With these we have 

 no concern in this place, having to deal only with the 

 curious little fish which is such a familiar denizen of the 

 shallow parts of our rivers, and, indeed, of the most 

 insignificant rivulets. 



The miller's thumb is an ungainly creature. Its utmost 

 length is about five inches ; the broadest part of its person 

 being across the head and gills, equal to about one-fourth of 

 the entire length of the fish. The eyes are on the top of the 

 head, as best fitted for the ground- haunting habits of their 

 owner, and have a greedy, sinister aspect. Each of the 

 foremost gill-covers carries a stout spine, an armature which 

 sometimes proves fatal to birds which try to swallow these 

 fish, for the miller's thumb, when he finds himself in jeopardy, 

 inflates his operculum, spreads abroad his great pectoral fins, 

 and tries to look as terrible as possible. These same pectoral 

 fins are no unpleasing feature, developed, as they are, into 

 broad and rounded fans. The ventral fins are reduced to the 

 nature of supports to the fish as it lies upon the ground. 

 The first dorsal fin has a rounded outline supported by eight 

 rays, and is both lower and much shorter than the second, 

 which has about seventeen rays. The ventral fin is greatly 

 developed, containing about thirteen rays. Altogether the 

 miller's thumb seems more amply provided with means of 

 propulsion and balancing than are many other fish which have 

 more use for them. 



In colour this fish is somewhat variable, but the skin, which 

 is without scales, has a grey ground colour, tending to brown 

 on the back spotted with darker brown. The sides are streaked 

 or mottled with brown, and this hue sometimes extends over 

 the belly, which is whitish. The male is generally darker 



