48. AMBLYOPSID^. 
323 
slender. Peritoneiiin silvery. Head in length ; depth about D. 
11 5 A. 8 ; Lat. 1. 50. L. 0 inches. Spawns in spring. Delaware River 
to Kansas and northward j abundant in the Great Lakes. One of our 
most remarkable fishes. 
(Agassiz, Lake Superior, 1850, 283; Gunther, vi, 207: Percopsis hammondi* Gill, 
Proc. Acad. Nat. Sci. Phila. 1864, 151.) 
Order N. IIAPLOMI. 
{The Haplomous Fishes.) 
Ko precoracoid arch. Parietal bones separated by the supraoccipital. 
A symplectic. Opercular bones present. Anterior vertebrae unaltered. 
Pharyngeal bones distinct, the superior directed forwards, three of four 
in number, the inferior not falciform. No interclavicles. Mouth with 
teeth. Air-bladder with a pneumatic duct. Ventral fins abdominal, 
rarely wanting; i)ectoral fins idaced low; dorsal fin more or less pos- 
terior, usually without spines. Head and body usually with cycloid 
scales. No adipose fin. Species chiefly inhabiting fresh water. (d-/owc, 
simple; shoulder; in aillusion to the want of the precoracoid arch.) 
(Physostomi iiart (families Esocidce, Umbridce, Cyprinodontidce and Heteropygii) Giin- 
ther, vi, vii.) 
ANALYSIS OF FAMILIES OF HAPLOMI. 
a. Margin of upper jaw formed by iiremaxillaries alone; ovoviviparous. 
b. Vent jugular; jiremaxillaries scarcely protractile Amblyopsid^, 48. 
bb. Vent abdominal ; x>remaxillaries freely protractile CYPP.iNODONTiDiE, 49. 
aa. Margin of upper jaw formed laterally by the maxillaries; premaxillaries not iiro- 
tractile. 
c. Jaws not produced; teeth villiform, equal Umbridce, 50. 
cc. Jaws produced ; teeth cardiform, unequal Esocidje, 51. 
Family XLVIII.— AMBLYOPSIDJ^. 
(The Blind- fishes.) 
Body moderately elongate, compressed behind. Head long, de- 
pressed. Mouth rather large, the lower jaw projecting; premaxilla- 
ries long, scarcely protractile, forming the entire margin of the u^iper 
jaw. Jaws and palatines with bands of slender villiform teeth. Bran- 
chiostegals about 6. Gill-rakers very short. Pseudobranchite con- 
cealed. Gill-membranes more or less completely joined to the isthmus. 
* Head larger, 3^ in length, exclusive of caudal ; dorsal higher, the longest ray 4J 
in length; anal higher, longest ray 6 in length; pectoral equals height of dorsal; 
ventral 5| in length, reaching vent, which is nearer snout than margin of caudal fin. 
Kansas. {Gill.) 
