OSTARIOPHYSI 581 



a distance, but this faculty is exhausted by continuous employ- 

 ment, and is recovered during repose. Although apparently 

 not exempt from exaggeration and fable, Humboldt's account in 

 Observations de Zoologie, p. 497, is recommended for further 

 information on the habits and modes of capture of Gymnotus. 1 



Fam. 3. Cyprinidae. Mouth usually more or less protractile, 

 toothless, bordered by the praemaxillaries and the maxillaries, or, 

 more frequently "by the praemaxillaries only. Parietal bones 

 united in a sagittal suture, or separated by a fontanelle ; oper- 

 cular bones well developed ; symplectic present. Lower pharyn- 

 geal bones falciform, subparallel to the branchial arches, pro- 

 vided with teeth arranged in one, two, or three series, and often 

 remarkably specialised. Eibs mostly sessile ; no parapophyses in 

 the thoracic region ; epipleurals and epineurals, mostly free, 

 floating. Pectoral fins inserted very low down, folding like the 

 ventrals. Body naked or scaly. No adipose dorsal fin. 



The brain-case is produced forward to the nasal capsule. 

 The branchiostegal rays are reduced to 3 ; the branchiostegal 

 membrane is usually more or less extensively grown to the 

 isthmus. The suborbital branch of the sensory canals is usually 

 produced on the operculum, as in the Characinidae. The ventral 

 rays number 7 to 12, rarely 5 or 6. Pyloric appendages to the 

 stomach are absent. 



Freshwater fishes feeding on vegetable substances or small 

 animals, and dispersed over the whole world with the exception 

 of South America, Madagascar, Papuasia, and Australasia. The 

 species are exceedingly numerous, about 1300 being known, 

 referable to four sub-families, as proposed by Sagemehl. 



(i.) CATOSTOMINAE. Margin of upper jaw formed in the middle 

 by the small praemaxillaries and on the sides by the maxillaries, 

 which are hidden in thick fleshy lips ; no barbels ; pharyngeal 

 teeth in a single row, very numerous, comb-like ; air-bladder 

 large, divided into two or three parts by transverse constrictions, 

 not surrounded by a bony capsule. Mostly from North America ; 

 two species from China and one from Eastern Siberia. Fossil 

 in the Lower Tertiary of North America. 



Principal genera : Sclerognathus, Carpiodes, Catostomus, Moxo- 

 stoma. 



1 For the anatomy and physiology, cf. C. Sachs's posthumous work, Untersuch- 

 n am ZUtfnml, odited by E. du Bois-Reymond (Leipzig, 1881). 



