8 MILLERS THUMB. 



Belfast and Londonderry. Thompson suspects there is some error in the record of this fish 

 being found in Ireland ; for it appears that other species of Cottus, as the Sea-Scorpion and 

 the Father-lasher, are occasionally called Miller's Thumbs in the North of Ireland. One 

 would suppose that if this fish was once introduced into Ireland, it would grow, thrive, 

 and multiply in the many suitable rivers of that country. From the well-known habits of 

 the fish to lurk frequently underneath stones, and to hide its dusky body among the gravel or 

 sand, it would be pretty secure from the attacks of enemies. However I should not advise 

 its introduction by any means into any waters where Trout or Salmon are found ; because 

 it is as I know a most voracious feeder, being especially fond of eggs and the newly-hatched 

 young ixy of other species of fish as well as of its own. 



I dissected two females the other day, about the 15th. of April; the ovaries were full 

 of eggs almost ready for deposition ; the stomachs of the same two fish also contained a 

 great number of their own ova as well as of several of their young newly-hatched fry. 

 Whether the males are guilty of such infanticide I do not know ; but I am positive about 

 the females. The spawn consists of a mass of pink eggs, rather large considering the size 

 of the fish ; and this mass, which generally covers an area of about one inch and a half to 

 two inches, and is about half an inch thick, is always deposited under stones, to which it 

 adheres by a mucous secretion which accompanies the eggs. The depressed form of the 

 fish's head is admirably adapted for insertion under stones, and when this has been accom- 

 plished, the female with her broad and muscular pectoral fins hollows out the sand or mud 

 under the stone, and then, probably, turns her abdomen round and deposits her eggs. The 

 spawning takes place in April and the beginning of May, according to my observation. 

 Johnston and Willughby say that the female collects the spawn into little lumps on her 

 breast, where it is covered with a black membrane until it is hatched. But I feel sure 

 there is some mistake here; the black membrane appears to be the membranous ovisac, 

 which is black in the Miller's Thumb. Linnaeus and Fleming say the fish forms a nest on 

 the ground and broods over it, and Blumenbach says the same. I have never found the 

 eggs except in a mass adhering to the under side of stones ; I think it probable, however, 

 that the male fish acts as a protector to the eggs, as is the case with the Stickleback. 

 Izaak Walton and some others assert that the Miller's Thumb continues to spawn for several 

 months. I have never found the eggs but in the spring of the year. 



I am told by one or two persons who have eaten this fish that it is very good indeed ; 

 when the head is excluded, however, there is but little left to eat. It is occasionally eaten 

 in Italy, and according to Pallas it is used as a charm against fever by some persons in 

 Russia; others "suspend it horizontally, carefully balanced by a single thread, and thus 

 poised, but allowed at the same time freedom of motion, they believe this fish possesses the 

 property of indicating, by the direction of the head, the point of the compass from which the 

 wind blows." — (Yarrell, i. 76.) The colour of the flesh after boiling is said to be pink like 

 Salmon ; but this is not true ; some of the fins occasionally turn slightly pink, but the flesh 

 remains as white as it was before boiling. 



The Miller's Thumb is supposed to resemble that organ in the miller, which is said to 

 assume a flattened form from frequently testing the flour. The head is very large, broad, 

 and depressed; a small curved, spine on the praeoperculum ; the body smooth and very slimy; 

 vent nearly midway between the snout and the tip of the tail ; body mottled with light and 

 dark brown ; belly white ; sides below lateral line spotted with black ; the lateral line very 

 straight ; first dorsal often fringed with orange red ; teeth small, villiform in both jaws and 

 on the vomer ; irides yellow ; pupils bluish black. 



The usual length of this fish is about four inches; one of five inches would be above 

 the average. The Miller's Thumb having the first dorsal fin with spines projecting above 

 the membrane is placed in the Acanthopter}'gian order; but the spines are quite blunt, and 



