Classification of the Order Ostariophysi. 27 



piremaxillaries are retracted, horizontal when they are 

 protruded. 



The Cypriiiiformes correspond to the family Cy|)rinida3 of 

 Giintiier, who, in 1868 (Cat. Fish, vii.), recognized four 

 principal divisions, which have been accepted by all subse- 

 quent authors. These groups have soinetiuies been regarded 

 as subfamilies, sometimes as separate families — Catosto- 

 midce, Cyprinidge, Cobitidge, and Homalopteridas. 



Family 1. Catostomidae. 



Prsemaxillaries small and maxillaries entering the gape; 

 lips usually fleshy ; no barbels. Pharyngeal teeth uniserial, 

 oiten numerous; pharyngeal processes of basiocci|)ital 

 uniting below the dorsal aorta to form an expanded perforated 

 lamella, rolled up at the edges, ending in a short blunt 

 process, and not covered with a horny sheath. Mesethmoid 

 broad, firmly united with frontals; subtemporal fossae siiallow; 

 a large later;. 1 occipital foramen on each side of the foramen 

 magnum ; paired fossae present in the temporal region, 

 open above and closed behind, but no posterior temporal 

 Ibssse. Cleithra normally suspended from supra-cleithra, 

 much expanded transversely. Air-bladder large, free, 

 divided into two or three parts by transverse constrictions. 

 Outer ramus of os sunpensorium strong, downwardly directed, 

 with a transverse laminar exj)ansion which meets its fellow ; 

 transverse process of second vertebra with a laminar expan- 

 sion directed downwards and backwards, united by suture 

 with the lamina of the os susjieiisorium. 



Principal genera: Cnrpiodes, Cydeptus, Catostomus, Xj/- 

 rnucherij Moxostoma, &c., with about sixty species fruin 

 North America. Mijxocyprinus, with two species from 

 Ciiina, is related to Carpiodes. 



Family 2. Cyprinidse. 



Praemaxillaries excluding maxillaries from gape ; one or two 

 pairs of barbels or none. Pharyngeal teeth, when present, m 

 one, two, or three series, not more than seven in one series ; 

 pharyngeal processes of basioccipital typically united below 

 the aorta to form a horizontal or oblique plate, flattish or 

 concave below, supporting a liorny pad *, and produced back- 

 wards into a strong process for the attachment of the retractor 

 museles of the lower pharyngeals. Mesethmoid broad, firmly 



* Ou tlie structure of tliis horny pad, see Gratziauow, Zool. Anz xxiii 

 19C0, p. (56. " ■ 



