202 FISHES OF ILLINOIS 



Order HAPLOMI 



(pike-like fishes) 



Skeleton bony; anterior vertebrae distinct, without Weberian ossicles; 

 ventral fins abdominal, rarely Wanting; all fins soft-rayed, although the 

 first dorsal ray is in a few forms somewhat stiffened and spine-like; no 

 adipose fin; pectoral arch suspended from the skull; mesocoracoid want- 

 ing (this character constituting the only important distinction between 

 these fishes and the Isospondyli); opercular bones well developed; air- 

 bladder with a distinct duct. Four families; species numerous and 

 widely distributed, chiefly inhabiting fresh or brackish waters of both 

 hemispheres. 



Key to Families of HAPLOMI found in Illinois 



a. Vent normal, not far in front of anal fin; eyes normal. 



b. Lateral line present; iaws duck-bill-like Esocidae. 



bb. Lateral line wanting. 



c. Upper jaw not protractile Umbridas. 



cc. Upper jaw protractile (the upper lip separated from the skin of the forehead 



by an evident groove, which passes wholly across the muzzle) 



Pceciliidae. 



aa. Vent jugular, in front of pectorals and close behind gill-openings; eyes more 

 or less concealed by thick skin; ventrals ordinarily wanting, or much 

 reduced Amblyopsidae. 



Family UMBRIDjE 



(the mudfishes) 



Body oblong, broad anteriorly and compressed behind; head some- 

 what flattened; scales cycloid, covering head and body; lateral line want- 

 ing; skeleton osseous; anterior vertebra? simple; no spines in fins; ventrals 

 abdominal; dorsal fin posterior; caudal rounded; no mesocoracoid; gill- 

 membranes little connected; branchiostegals 6 to 8; pseudobranchiae hid- 

 den, glandular; gill-rakers little developed; mouth moderate, premaxil- 

 lary not protractile; lateral margin of upper jaw formed by the maxilla- 

 ries, which are toothless and without distinct supplemental bone; pre- 

 maxillaries, lower jaw. vomer, and palatines with bands of villiform or 

 cardiform teeth; stomach without blind sac; no pyloric caeca; air-bladder 

 simple, with distinct duct; oviparous fishes. 



