. 31. CYPKINID^E SQUALIUS 231 



hooked, with narrow grinding surface or none. (Grinding surface 

 present in Squalius leuciscus, obsolete in most of our species.) Anal 

 basis short or somewhat elongate. Dorsal tin posterior, usually behind 

 ventrals. Intestinal canal short. Size generally large. A very large 

 group, one of the largest current genera in ichthyology, represented by 

 numerous species in the rivers of Europe, Asia, and North America. 

 Most of our species have been poorly defined. The majority of Girard's 

 original types have been preserved, and the descriptions here given are 







mainly taken from them. Much larger series of each form are neces- 

 sary before the species can be properly discriminated. Individual irreg- 

 ularities in dentition are common in this genus. (From squalus, a 

 shark; some early writers on ichthyology having called the typical spe- 

 cies Squalus minor, for no evident reason.) 

 The species may be divided as follows : 



* Teeth normally without grinding surface. 



t Caudal peduncle not very stout, its least depth not two-thirds the length of the 



head. 



t Mouth very wide, the lower jaw much projecting beyond upper, the upper lip 

 on the level of the middle of the pupil, and the maxillary reaching to be- 

 low the pupil ; body elongate, compressed ; dorsal well backward (CLi- 



NOSTOMUS Grd. ) elongatus, vandoisulus, estor, funduloides. 



It Mouth moderate or small, terminal, oblique, the lower jaw little projecting, 

 premaxillary below the level of the pupil, and the maxillary not reaching 

 to the pupil. (TiGOMA Grd.) 



a. Anal basis elongate, its rays 10-12.. ..lujdroplilox, tcenia, montanus, hnmboldti. 

 aa. Anal basis short, its rays 8 or 9. 

 1). Scales in lateral line 50-65. 



cruoreus, ardesiacits, pandora, margaritus, gula, pulclier, 

 egregius, lineatus, graciUs, conformis, bicolor, obesus, purpurcus. 

 bb. Scales in lateral line G5-80. 



pulchellus, intermedius, aliciw, copei, niger, conspersus. 



tt Caudal peduucle very deep and compressed, its least depth nearly equal to the 

 greatest depth of the head ; dorsal over veutrals ; scales rather large 



(SiBOMA Girard) . . , gibbosus. 



** Teeth with evident grinding surface. (SQUALIUS.) 



o. Robust species, the depth 3-3 in length ; lateral line less than 60. 



rhomaleus, squamatus, atrarius, crassus. 



cc. Slender species, the depth 4-4J in length ; lateral line 60-70 (CHEONDA 

 Grd. ) cocruleus, cooperi, nigrescens, modestus. 



* Teeth (normally) without grinding surface (various irregularities often present, so 



that the character has little value). 

 t Caudal peduncle not very stout, its least depth not two-thirds the length of the 



head. 



t Mouth very wide, the lower jaw much projecting beyond upper, the upper 

 lip on the level of the middle of the pupil, and the maxillary reach- 

 ing to below the pupil ; body elongate, compressed ; dorsal well back. 

 (Clinostomus Girard.*) 



* Girard, Proc. Acad. Nat. ScL Phila. 1856, 211: type Luxilus elongatus Kirtland 

 (Azi>ca, to incline; 6TO/.KX, mouth.) 



