246 PATAGONIAN EXPEDITIONS : ZOOLOGY. 



k. Caudal widely forked, the upper lobe produced in a filament ; a single max- 

 illary barbel. Pseudostegophiliis Eigenmann & Eigenmann. 

 kk. Caudal emarginate. 



/. A single maxillary barbel. Henonetna Eigenmann. 



//. Two maxillary barbels. Homodicetus Eigenmann. 



kkk. Caudal rounded. 



m. A single maxillary barbel. Stegophihis Reinhardt. 



mm. Two maxillary barbels. Mmroglanis Eigenmann & Eigenmann. 



jj. "Rimae branchiales confluentes, membrana branchiostega cum isthmo gulare 



baud connexa;" caudal rounded; maxillary barbel single; no accessory 



caudal rays. Acanthopoina Liitken. 



//. No labial teeth ; teeth in the jaws in a single series. 



n. Teeth pointed, in a single series in the intermaxillaries only ; mouth sub-inferior ; 



a single ma.xillary barbel. Vandcllia Cuvier & Valenciennes. 



uji. Teeth broad, incisor-like in both jaws ; caudal forked ; two ma.xillary barbels. 



Pareiodon Kner. 



5. NEMATOGENYS Girard. 



Nematogenys Girard, Proc. Acad. Nat. Sci. Phila., VII, 1854, 198 

 [inermis). 



Type : Trichomyctenis inermis Guichenot. 



Dorsal fin placed over the ventrals, without a spine. Fontanel ex- 

 tending to base of occipital process, interrupted above the posterior margin 

 of orbit. Opercle and preopercle unarmed. A single barbel on each 

 maxillary and one pair of mental barbels. 



Habitat : Central Chili. 



9. Nematogenys inermis (Guichenot). 



(Plate XXXI, Fig. 2, and Plate XXXII, Fig. 2.) 



Trichomyctenis inermis Guichenot, in Gay Hist. Chile Zool., II, 312, pi. 

 ix, fig. 2, 1848 (Chili). 



Nematogenys inermis Girard, Proc. Acad. Nat. Sci. Phila., VII, 1854, 

 198; id. U. S. Naval & Astron. Exped. 240, pi. xxxii, 1855 (Rio de 

 Maypu near Santiago); Philippi, MB. Ak. Berl., 716, 1866 (Chili); 

 Giinther, Cat, V, 272, 1864 (copied) ; E. & E. Proc. Cal. Acad. Sci., 

 2d Sen, II, 50, 1889 (Curico; Santiago); id. South Am. Nematog- 

 nathi, 322, 1890 (Curico; Santiago). 



Nematogenys nigricans Philippi, /. c, 716 (Chili). 



Nematogenys pallidns Philippi, /. c, ']i6 (Chili). 

 Habitat: Fresh waters of Central Chili. 



