EIGENMANN : FRESH WATER FISHES. 235 



I'ordre suivant: Velasia cliilensis, Geotria australis, Exoniegas macrosto- 

 mtts, et enfin notre exemplaire, on voit une serie continue de developpe- 

 nient de ce plus-ou-moins. Les termes de cette serie, s'ils se trouvent 

 constants a des differents locaux, peuvent naturellement etre regardes 

 comme des esp^ces distinctes ou des formes locales — c'est 1^ une question 

 de convenance — mais certainement ils ne meritent pas d'etre des types 

 generiques." 



Larvae very similar to those of Pefroniyzoii hut with more than 80 

 preanal myomeres ; a triangular nasal opening ; dentition simple, a lingual 

 tooth with 3 points, of which the median is very small ; suctorial teeth 

 radially arranged, papillary; no median, supraoral or infraoral teeth; 

 mouth bordered by cutaneous lamina ; dorsals remote. 



Distribution of the Species : Gal legos to Rio de la Plata. 



a. Back rounded ; a gular pouch. 3. viacrostomus. 



aa. Back with a flattened area bordered by two dermal folds, merged behind and continued in 

 front on the snout ; no gular pouch. 4. maa'ostoiniis gallegensis. 



3. ExoMEGAS MACROSTOMUS (Burmcister). 



Petromyzon macyostouiiis Burmeister, Anal. Mus. Buenos Aires, 1868; 

 Act. Soc. Paleont. XXXVI ; Giinther, Cat. Fish. Brit. Mus. VIII, 

 506, 1870. 

 Exomegas macyostomiis G\\\, Proc. U. S. Nat. Mus. V, 524, 1882; id. Sci- 

 ence XXIII, 30, Jan. 19, 1894; id. Proc. U. S. Nat. Mus. XVII, no, 

 1894. 

 Geotria macrostomns Berg, Anales del Museo de La Plata I, 2, plate i, 

 1893 (Island of Flores, near Montevideo). 

 This species, if distinct from the variety gallegensis, is known from but 

 two specimens ; one, 40 cm. long, described by Burmeister was found 

 alive in the Calle de Mexico in Buenos Aires in 1867, immediately after 

 a heavy rain ; the second, 44 cm. long, was obtained in 1890 and was 

 recorded by Berg. If distinct from the Gallegos specimens, this species 

 is extralimital. 



"No teeth in the circumference of the mouth; outer row of the lo-ii 

 concentric series largest, about 24 on each side ; gular sack large." Berg. 



