GASTEROSTEIDiE. 243 



fish placing his snout on the end of each straw, and then raising his body vertically 

 to press it clown. Conferva? and such like are then woven into a mass above, 

 through which the water can have free passage. In the centre of this, a dome- 

 like hollow is preserved, and on the top a small round hole whose edges are 

 strengthened with particular care, and rounded off by tucking in the loose fibres. 



From this time as described by Mr. Warrington (Ann. Nat. Hist. (2) xvi, 1855, 

 p. 350) the nest was opened more and more to the action of the water while the 

 male hovered over it, causing a current of water to be propelled across the surface 

 of the ova, this action being almost constantly repeated. After about ten days 

 the nest was destroyed and minute fry appeared and were guarded by the male. 

 (Other observers have found the eggs to take three weeks or nearly a month 

 before they were hatched.) Also if the young fish strayed above a certain distance 

 from the nest they were brought back by puffing at them by the male. As soon 

 as the yelk bag became absorbed and they could swim he gradually relaxed his 

 efforts. 



They have also been observed to select, as suitable places for constructing 

 their nests, rock pools which are only reached by the spring tides. Here the 

 temperature of the water is considerably increased by the heat of the sun, and the 

 young are hatched and reared in comparative security. 



Diseases. — Mr. Wolley (Zool. 1847, p. 1649) mentions a disease among the 

 sticklebacks in a pond near Liverpool : it appears as large globular excrescences 

 each the size of a peppercorn, but taken together equalling the size of the body of 

 the fish. The fish are small and ill-conditioned. Tait (Journ. Anat. and Phys. 

 v, 1869, p. 12) has described how these fishes are affected by tumours, which are 

 soft and sensitive, impeding the movements of the fish. 



Thompson (Nat. Hist. Ireland, iv, p. 87) observed that the largest examples 

 of the variety G. brachycentrus, invariably found where the temperature was 

 lowest, were perfectly free from the pearl-like tumours which adhere to the body 

 and infest those inhabiting the comparatively warm waters of the lower grounds. 



It has been observed that wounds received from one another in conflicts at 

 first become white, then increase in extent until the whole fish is covered with a 

 furry-looking fungus (Wakefield, Zool. 1853, xi, p. 3760). 



Mr. Poole (Nature, Sept. 1881, p. 485) remarks having found these fish in a 

 pond at Godalming infested by numbers of Infusoria, evidently parasitic, upon 

 them. The parasite being apparently Trichodina pediculus which previously had 

 only been known to be parasitic on fresh water Polypes, as the Hydra, but which 

 it now seems also employs the stickleback as its host. 



Uses. — In Eastern Russia, also in the Baltic, numbers are collected during 

 November, when they assemble on the coast in shoals prior to seeking their 

 winter quarters. They are boiled down, a bushel, it is reported, giving about two 

 gallons of oil, and the refuse fish is employed as manure. Near Dantzic they are 

 likewise said to be used for feeding ducks and fattening pigs. In Kamtschatka 

 and in Rupert's Land they are stored up for the winter food of dogs. 



As food. — A nourishing soup it has been observed may be made from stickle- 

 backs. 



Habitat. — Greenland, Northern Europe, and North America. In the Orkneys 

 fouud in even the smallest brook, lock, or puddle that has a running communication 

 with any other piece of water (Low). It is common not only inland but all 

 round the coasts of Great Britain and Ireland. 



The marine, semi-marine, and estuary varieties have been specially recorded 

 from the following localities. Variety trachurus around the coast in salt or 

 brackish waters: common in the Orkneys and Zetland: Banff (Edward): 

 Aberdeen (Sim) St. Andrew's: Aberlady, but not common in the Firth of Forth, 

 frequent at Berwick-on-Tweed (Parnell) : also found in Ayrshire (Thompson) : 

 abundant in Yorkshire (Clarke) : swarms in Lincolnshire and common in 

 Norfolk : mouth of the Thames : Isle of Wight (More) : Weymouth (Gosse) : 

 Devonshire, Cornwall, and Somersetshire. In Ireland this form and also the 

 variety semiloricatus are found as marine or estuary residents in the island of 

 Rathlin. The typical tracfwrus has been taken in Lame Lough: Belfast Bay 



16* 



