82 TELEOSTEI : HAPLOMI. — XIV. 



Family XXXV. PERCOPSID^. (Tiik Tkou r Pkrches.) 



liody eloiiji.'itL', covitlmI with iiiudiTato-sizetl, thin, !«tronj^l_v ctenoid 

 scales; head naked; no barbels; openles well developed; gill open- 

 ings wide ; an adipose tin ; mouth small, horizontal ; teeth very 

 small, villiform; no teeth on vomer or palate; margin of upper 

 jaw formed by premaxillaries alone, these short and not protrac- 

 tile; gill rakers tubercle-like; cavernous structure of the skull 

 highly developed, as in Stellij'crus, Accrina and Eru-ymha ; fins muili 

 as in Sdlmoiiidcc ; pellucid ; branchiostegals G ; stomach siplional 

 with about 10 pyloric ca?ca; ova large; no oviduct. A single sj)e- 

 cies inhabiting cold fresh waters in the northern U. S. Interest- 

 ing little fishes, with the general characters of Salmonida, but 

 having the mouth and scales decidedly IVrch-like. 



84. PERCOPSIS Agassiz. (nepKn, jjcrch ; o^j/n, appearance.) 



195. P. guttatm a Agussiz. Tuorx rKUCU. Silvery ; upper 

 parts with rounded dark spots made up of minute dots ; lower jaw 

 included; tail long. Head 3^; depth 4 J. D. 11. A. 8. Lat. 1. 

 60. L. 10. Great Lakes and tributaries, rarely S. ; Ohio 11. 

 (Jordan) ; Potomac R. (Baird) ; Delaware 11. (Abbott) ; Kansas 

 (Gill). (Lat., spotted.) 



OuDKK XIV. HAPL03II. (The Pike-like Fishes.) 



This order differs from the other soft-rayed fishes, chiefly in the 

 simpler structure of the shoulder girdle, which lacks the pra>coracoid 

 arch. There is never an adipose dorsal ; the dorsal is posterior in 

 position and tlie head is depressed and usually more or less scaly. 

 The ])seudobranchiu' are wanting or glandular. The group is made 

 uj) chiefly of fresh-water species. (dTrXoor. simi)le; w/ioj, shoulder.) 



Family XXXVI. AMBLYOPSID.^ (Tiik Cavk 



FiSIIKS.) 



Body elongate, with long depressed head ; mouth large, the lower 

 jaw ]irojecting; premaxillaries scarcely protractile, forming whole 

 edge of upper jaw; teeth villiform; eyes sometimes rudimentary 

 and concealed under the skin; hejwl naked, with papillary ridges; 

 body with small, cycloid scales, irregularly arranged; no lateral 

 line; D. far V)ack, opposite A.; C. rounded; V. sniull. or wanting; 

 vent at the throat, as in Aphntlodrrus ; gill membranes joined to 

 isthmus; stomach csecal, with pyloric ajipendages ; some (iind 

 probably all) viviparous. Genera 3; species .'). 



Fisiies f>f small size livin'j in subterranean streams and ditches of 

 the central and southern U. S., probably remnants of an ancient 

 fauna. 



