Class/Jicalion of the Order Ostariophysi. 27 



praMiiaxillaries are retractccl, horizontal wlicu tlicy are 

 protrudtMl. 



The Cyi)rinit'()rmes conospoiul to the family Cyprinidre of 

 Giinthcr, who, iu 1868 (Cat. Fish, vii.), recognized four 

 ])riiici[)al divisions, which liave been accepted by all subse- 

 quent authors. Tiiese groups have sometimes been regarded 

 as subfamilies, sometimes as scjiarate families — Catosto- 

 midre, Cyprinida% Cobitida^, and Homalopteridse. 



Family 1. Catostomidse. 



Pra?maxillaries small and maxillaries entering the gape; 

 lips usually tleshy ; no barbels. Piuiryngeal teeth uniserial, 

 olten numerous; ])haryngeal processes of basioccipital 

 uniting below ihe 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 fossge shallow; 

 a large lateral occipital foramen on each side of the foramen 

 magnum ; paired fossa? present in the temporal region, 

 open above and closed behind, but no posterior temporal 

 fossse. 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 suspensorium strong, downwardly directed, 

 with a transverse laminar expansion 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 0.9 suspensorium. 



Principal genera : C'npiodes, Cycleptus, Catostomus, Xt/- 

 raucheny Alo.vostoma, &e., with about sixty species from 

 North America. Mfjxocyp)rinus, with two species from 

 China, is related to Carpiodes. 



Family 2. Cyprinidae. 



Prsemaxillaries excluding maxillaries from gape ; one or two 

 pairs of barbels or none. Pharyngeal teeth, wlien present, ni 

 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 horny pad"^, and produced back- 

 wards into a strong process for the attachment of the retractor 

 muscles of the lower pharyngeals. Mesethmoid broad, firmly 



* On the structure of this horuy pad, see Gratziauow, Zool. Aiiz. xxiii. 

 1900, p. GG. 



