Jordan and Evermann. — Irishes of North America. 745 



337. PYGOSTEUS, Brevoort. 



Pygosteus (Brevoout) Gill, Cat. Fishes East (.'oast N. A., 39, 1861; name only. 

 Pl/gosteiis, Gill, Canadian Naturalist, ii, 8, 18G5, {occideulalii}. 

 Gofleronlen, SAfVAGF., Revision des Kpinoches, 29, 1874, {imngitius). 



This genus ia characterized by the presence of 9 to 11 divergent spines 

 and by the weakness of its innominate bones. As in Eucaliti, tlie gill 

 membranes form a broad fold across the isthmus. Vertebrae 14 + 18 = 32. 

 Species 2, in northern regions, the following cosmopolitan ; a second, 

 Pygo-steuh' sinensis, Guichenot, from China. {T^vyi/, pubic region; oartov, 

 bone.) 



1097. PYGOSTEUS Pl'XOITIUS (Linmeus). 

 (NiNE-spiNF.D Stickleback.) 



Head 4 ; depth 5 to 6. D. VIII or IX-I, 9 ; A.I, 8. Body very slender, 

 somewhat compressed, tapering into the very long and slender caudal 

 peduncle, which is much depressed and strongly keeled, broader than 

 deep. No dermal bony plates along sides ; small plates along bases of 

 dorsal and anal, and on caudal keel; skeletal plates not at all covered by 

 skin. Postpectoral plate well developed, striated. Head shortish, the 

 snout rather blunt. Eye large, longer than snout. Thoracic processes 

 well developed, widely divergent, forming a U-shaped figure. Bones of 

 skull granulate, its surface bones all weak. Dorsal spines moderate, the 

 anterior diverging to the right or left at various angles, the posterior more 

 nearly erect; anal spine large, larger than the dorsal spines ; pubic bone 

 feeble, lanceolate, not carinated, its edges raised, its median part thin; 

 ventral spines moderate, serrulate, their length more than i that of the 

 head; caudal lunate, long and narrow. Gill rakers long and slender; gill 

 membranes free from the isthmus posteriorly. Olivaceous above, profusely 

 punctulate, irregularly barred with darker; silvery below. Length 

 3 inches. Northern parts of Europe, and Atlantic coasts of America from 

 Long Island to the Arctic Sea, also in tributaries of the Great Lakes, and 

 northward to the Saskatchewan and Alaska, where it abounds in the 

 mountain lakes and streams ; a widely distributed species, found in both 

 fresh and brackish waters. (jJungitius, pricking.) 



Gasterostens piinijiliiix, LiNN.T.rs, Syst. Nat., Ed. x, 20fi, 175S, Europe; after Gaslerosleus anileia 

 in durno decern, AuTEni; Walbaum, Artedi Pise, 1792,146; GCnther, Cat., i, 6,1859; Jordan 

 & Gilbert, Synoiisis, 393, 1883. 



Pi/gosteua pnnijitius, Eigenmann, Proc. Ac. Nat.Sci. Phila., 1886,235. 



Gasterosteus Ixois, CuviER, Kcgne Animal, Ed. 2, ii, 170, 1829, streams of France. 



Gasteronleitsoccidentah.", CvvJF.n &\\-LT.tiriEyiiES, Hist. Nat. Poiss., iv, 509, 18J9, Newfound- 

 land; not G. occidentalis of LiNN.Kis, which is an unrecognized species, probalily of 

 Caranijidie. 



Gasteronkus cnnrinnns,* Riciiardshx, Fauna Bor.-Anifr'., in, .57, 1836, Saskatchewan River 

 and Great Bear Lake; UeKay, N. Y. Fauna: Fishes, 68, 1842. 



Giistcrosletis viainensif,^ Storei:, Bost. Journ. Nat. Hist., i, 1837, 464, Kennebec County, Maine. 



*The names conciimus and uebulosiis have been used for the fresh-water form of the northern 

 inland lakes, but a comparison of specimens from Calumet River, Illinoi.s, with others from 

 Massacliusetts shows no tangible difference. We liave seen none with less than 9 dorsal spines. 

 Nor can we separate the American form called occidentalis from the European pioujUius. Bean 

 records no difference between Hudson Bay specimens and those from Massachusetts. 



t These two names may represent a distinct subspecies, mainentss, distinguished by the presence 

 of 7 free dorsal spines. 



