838 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xs 



anterior unmodified. Eel-like lishes, widely distributed in warm seasj 

 and in fresh waters. The species are few, l)iit hiohly diversified inl 

 structure, constituting two su))orders and foui' families. They are' 

 prob:i])l3' r<4ated to the Ap<>de><^ but this is not certain, and in the 

 stiucture of the head they approach more nearly to the true fishes. 

 The}' represent degraded rather than primitive types, and the line of 

 their descent is as yet unknown. It is not even certain that the forms 

 grouped in this order are closelv related, (aw together; (iftocyxioc^ 

 gills.) 



Family I. MONOPTKRID.^. I 



ri(;e-fieij) eels. 



Bod}' elongate, naked; tail short, tapering to a point; no barbels; 

 margin of the upper jaw formed by the premaxiilariivs, the maxillaries 

 well developed, l3'ing behind them and parallel with them; lips thick; 

 palatine teeth small, in a narrow band; gill openings confluent into a 

 ventral slit, the mem})ranes united to the isthnms; gill arches three, 

 with the gill-fringes rudimentary, and with moderate slits between 

 them; no accessor}' ])reathing sac; lateral line present; no pectoral or 

 ventral fins; dorsal and anal reduced to Ioav folds; ribs present; no air 

 bladder; stomach without ca^cal sac or pyloric appendages. Ovaries 

 with oviducts. Vertebrae 100 + 88 = 188. 



Eel-like fishes of the rivers of eastern Asia, everywhere abundant, 

 probably all reducible to one single species. 



1. MONOPTERUS Lacepede. 



3fonop/er».s Lacepede, Hist. Nat. ]\)iss., II, 1798, p. 139 {jdnniciiiii!^). 



Fluta HcHNEiDER, Syst. Ichth., 1801, ji. 5(>5 {javitnensis). 



Ophicardia McChKLLAND, Calcutta Jourii. Nat. Hint., V, p. 191 (phaijriana). 



Apterigki Basilewsky, Nouv. Mem. Soc;. Nat. INIosc, X, 18.^5, p 247 [me.cogularis). 



Characters of the genus included al)()vc. (/"''''>?, one; Trrfpor, fin.) 



I. MONOPTERUS ALBUS (Zuiew). 



Murxna alba Zuiew, Nov. Act. Ac. Sci. Petropol, 1793, p. 299, pi. vn, fig. 2. 



Munoptenis javanois Lacepede, Hist. Nat. Pois.s., II, 1798, p. 139, Java. 



Monopterus javanensis Scn^EiDER, Syst. Ichth., 1801, p. 565, after Lacepede. — Can- 

 tor, Malayan Fish, 1850, p. 339, pi. v, figs. 6-8.— Bleeker, Atlas Ichth. Mur. 

 1864, p. 118, pi. xLvii, fig. 1, Java, Sumatra, Banka, Bintang, Borneo, Cel- 

 ebes. — GtiNTHER, Cat. Fish., VIII, 1870, p. 14, Batavia, Borneo, Sarawak, 

 Siam, Formosa, Chusan, Hongkong, Ningpo, North China, Japan, and of 

 authors generally. 



Umhrarichapeitura hrris Lacepepe, Hist. Nat. Poiss., V, 1803, p. 658, i)l. xvii, 

 fig. 3. 



Monopterun lurii^ KicnxRDsos, Voy. Sulphur, Ichth., p. 116, Hongkong. 



Syinbranchus eurychusina Bleeker, Verb. Bat. Gen. Murajn, XXV, p. 60. 



Op/uoardmp/iaynana McClelland, Calcutta Journ. Nat. Hist., V, pp. 191, 218, 

 pi. XII, fig. 1 , River Ganges. 



