31. CYPRINID^E - HYBOGNATHUS. 155 



180. Z. sidermm (Cope) Jor. 



Physiognomy of Apocope. Body fusiform. Head rather small, acu- 

 minate. Mouth terminal, the upper jaw the longer, maxillary reaching 

 line of orbit. Mouth forming more than a semicircle. Lower jaw hard, 

 less attenuate than is usual in Hybognathm. Eye small, 4yL in head. 

 Fins long, the ventrals reaching anal. Color dark iron-gray a.bove, a 

 darker band of the same along the sides, above the lateral line, extend- 

 ing from the end of the snout to the middle of the caudal. Head 4 ; 

 depth 4. D. 8; A. 7; Lat. 1.88; teeth 4-4. Arizona. (Cope.) 



(Hyborliynchus sidcrius (lapsus for Hybognathus) Cope, Zool. Wheeler's Expl. W. 100th 

 Mer. v, 670,1870.) 



** Scales moderate, 55-60 in the course of the lateral line. 



181. Z. pluoaibcmn (Grtl.) Jor. & Gilb. 



Body rather slender. Head moderate, rounded in front. Color uni- 

 form, sometimes a black spot at the base of the caudal. D. 8 ; A. 7 ; Lat. 

 1. 58 5 teeth 4-4. Arkansas and Indian Territory. (Girard.) This spe- 

 cies may, perhaps, be referable to Hybognathus. 



(Dionda plumbea and spadicea Girard, Proc. Acad. Nat. Sci. Phila. 1856, 178 : Hylo- 

 rhynchus puniccus, Grd. 1. c. 179 : Dionda grisea, Grd. U. S. Pac. E. E. Surv. x, 230.) 



. HYBOGNATHUS Agassiz. 



(Algoma and Dionda Girard.) 

 (Agassiz, Anier. Journ. Sci. Arts, 1855, 223: type Hybognathus nuchalis Ag.) 



Body elongate, somewhat compressed. Mouth horizontal. The jaws 

 normal, sharp-edged; lower jaw with a slight, hard protuberance in 

 front; no barbel; upper jaw protractile. Teeth 4-4, cultriform, with 

 oblique grinding surface and scarcely any hook. Alimentary canal 

 elongate, about 4 times the length of the body. Peritoneum, black. 

 Scales large. Lateral liue continuous. Dorsal over ventrals. Anal 

 basis short. Size moderate. Species numerous ; mostly southwestern, 

 and little known. (/??, gibbous ; fva.0o~, jaw.) 



* Body comparatively elongate, little compressed, the depth less tbaii two-sevenths of 



the length. 

 a. Suborbital bones comparatively long and narrow. 



slightly included; the premaxillary below the level of the eye: the maxillary just 

 reaching the front of the eye. Lower jaw thin-edged, with a slight syuipbyseal knob. 

 Eye sruall, 6 in head. Scales small. Lateral line complete, decurved. Dorsal 

 slightly behind ventrals. Dusky bluish above ; everywhere with dark points. A 

 black spot at base of caudal. Head 4 ; depth 4-ld. D. 8 ; A. 7 ; scales 10-56-8; teeth 

 4-4. L. 7 inches. Lake Tupataro, Guanajuato, Mexico (west of the Sierra Madre). 

 (Jordan, Proc. U. S. Nat. Afr- iro w.o s 



