C YPRINIFORMES 37 5 



cellular as in Erythrinus ; in Citharinus there is an accessory respiratory 

 diverticulum of the gill-cavity. There are many pyloric caeca and an 

 adipose tin [379]. 



Tetragonopterus, Ag. ; Tertiary, Brazil. Hydrocyon, Cuv. ; Alestes, 

 M. and T. — -Africa. Crenuchus, Giinth. ; Brycon, M. and T. ; Chalceus, 

 Cuv. ; Serrasalmo, Lac. ; Piabucina, C. and V. — America. Distichodiis, M. 

 and T. ; Citharinns, Cuv. — Africa. Macrodon, M. and T. ; Erythrinus, 

 Gron. — America. Phago, Giinth. ; Neoborus, Blgr. ; Xenocharax, Giinth. 



Family Cyprinidae. The scales are cycloid ; sometimes they are 

 absent, and in the leather carp variety of Cyprinus they are represented 

 by only a few very large scales on the body. Barbels are often present. 

 The mouth has a small gape, is usually protractile, toothless, and 

 margined only by the premaxilla (Figs. 327, 358). The protractility 

 of the jaw in the Cyprinoid has doubtless been acquired independently 

 of that of the Acanthopterygii, and differs fundamentally from it in the 

 manner in which it is brought about (Sagemehl [379]). In the Carps the 

 dorsal processes of the premaxillae are short, do not reach the cranium, 

 but are joined to it by a ligament in which lies a median ' rostral ' bone 

 (Fig. 327). It is by the stretching of the ligament and motion of the 

 rostral that the jaw is brought forward. The rostral is a specialised 

 portion of the ethmoid cartilage. In the Catostominae the maxilla still 

 contributes to the margin of the mouth. A fenestra is present in the 

 exoccipital. The lower pharyngeals (fifth branchial arches) are strong 

 and armed with powerful teeth, which in many genera bite against a 

 horny pad borne on a ventral process of the basioccipital (Fig. 358). 

 A sensitive palatal organ is situated in front of this masticator. 



The second and third dermotrich of the dorsal and pectoral fins are 

 often serrated spines. There are no pyloric caeca. 



In Cobitis, Homaloptera, and their near allies the air-bladder is small,, 

 with a subdivided cavity, and is partially or entirely enclosed in a bony 

 capsiile, apparently formed by the ossification of its walls. This affords 

 a very interesting case of parallelism when compared with certain of the 

 Siluroidei (p. 377), in which the reduced air-bladder is also encapsuled r 

 but by very different means. Gastromyzon is remarkably flattened 

 ventrally, its expanded paired fins contributing to form a sucker-like 

 surface of attachment. 



Rhodeus, and allied genera, are remarkable for the development of a 

 long ovipositor, a tubular outgrowth from the urinogenital opening of the- 

 female. 



Sub-Family 1. Catostominae: The 'Suckers.' Sclerognathus, Gthr. ; 

 Catostomus, Le S. (Fig. 361) ; Carpioides, Raf. ; Moxostoma, Raf. — N. 

 America ; some in Tertiary deposits. 



Sub -Family 2. Cyprininae : The Carps. Carp, Cyprinus, L. (Fig-. 

 362) ; Barbel, Barbus, Cuv. ; Gudgeon, Gobio, Cuv. ; Minnow, Leuciscus, 

 Klein ; Tench, Tinea, Cuv. ; Bltodcus, Ag. ; Aspius, Ag. — Europe, and 

 to Miocene or Oligocene. Catla, C. and V. ; E. Indies. Labeo, Cuv. ; 

 Africa and Asia. Rohteichthys, Bleek ; Leptobarbus, Bleek.— E. Indies. 

 Luciosoma, Blkr. ; Hypophthalmichthys, Blkr. — China. Bream, Abramis, 

 Cuv. ; Alburnus, Heck. — Northern hemisphere. 



