Gastrosteidac 35 



which a rather strong spine projects ; its coloration is ohv c 

 spotted, marhled or liarred witli hro\Yn or l)lack. It is found all 

 over Europe, except the Iherian Peninsula and Greece ; in our 

 islands it seems to he ahsent from Scotland and Ireland. It lurks 

 on the hottom or under stones, waiting for the small fishes, 

 worms, etc., on which it feeds. In March or April the Bullheads 

 pair and scoop out a hole under a stone, forming a nest ; the 

 eggs are adherent, and are usually attached to the under side of 

 this stone ; the male guards the nest until the fry swim away. 

 The usual length of this species is 3 or 4 inches ; exceptionally 

 6 inches may he attained. The exhihited specimen is from a 

 brook at Selborne, and was presented hy Dr. E. Bowdler Sharpe. 



GASTEOSTEIDAE. 



The Gastrosteidae are a northern family ; they are distinguished 

 from other fishes found in our rivers in having the spines of the 

 spinous dorsal fin free, unconnected by membrane. 



62, 63. Three = spined Stickleback, Gastrosteus aculeatus. — 

 This little fish is never more than 4 inches long ; its dorsal fin 

 has three (rarely two or four) spines. It is found on the coasts 

 and in the rivers of arctic and north temperate countries ; in the 

 arctic regions it is principally marine, and in Southern Europe it 

 appears to be strictly a fresh-water fish. The development of a 

 lateral series of bony plates is very variable, but as a rule the 

 series is complete in marine Sticklebacks and is reduced to 3 or 4 

 anterior plates in those from inland localities. The Three-spined 

 Stickleback is famous for its boldness, greediness and pugnacity. 

 In the spring or summer the male fish acquires a brilliant red 

 colour on the belly and builds a nest, a dome or barrel-shaped 

 structure made of bits of the roots and stalks of water-weeds 

 cemented together by a secretion from his kidneys ; when the nest is 

 made he seeks a mate, often fighting to win her, and after the eggs 

 are laid he guards the nest until the young fish desert it. The model 

 exhibited (62) is the work of the donor, F. Page, Esq. A male in 

 breeding dress is also shown (63). 



64. Ten = spined Stickleback, Pjjgosteus i)}in(iitius. — The 

 spinous dorsal fin is represented l)y a series of about ten small 

 spines, alternately divergent to the right and left ; the body is 

 naked except for a few small plates bearing a keel on each side of 

 the tail ; the maximum length is 3 inches. This is a northern 

 species, and in Europe does not cross the Alps ; it varies in 



