284 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



Of this widely distributed family, whose species are chiefly marine, two 

 genera with five species are found in South American fresh waters. Two 

 of the species are found in Patagonia, two others are confined to Central 

 Chili, and the fifth is found near Buenos Aires. The genera may be distin- 

 guished by the following characters : 



a. Two dorsals ; pectoral asymmetrical, upper rays longest ; ventrals below or a little behind base 

 of pectoral. Tongue smooth ; scales ciliate; vertebrae 33-35. 



b. Maxillary with supplemental bone ; ventral below posterior edge of base of pectoral ; 



palatine toothed ; scales small. Percichthys. 



bb. Maxillary without supplemental bone ; ventral a little behind base of pectoral ; palatine 



toothless ; scales larger. Pcrcilia. 



13. PERCICHTHYS Girard. 



Percichthys Girard, Proc. Acad. Nat. Sci. Phila., VII, 1854, 197 and U. S. 

 Naval and Astronom. Exped. 230, 1855. [tnicha.) 

 Type: Perca trucha Cuvier & Valenciennes. 



Species of Percichthys. 

 a. Depth less than length of head. 



b. Sides of head and body usually spotted ; highest dorsal spine less than half the length of 



head in adult ; scales 8 to 10-59 to 67-22 to 25. 25. trucha. 



bb. Sides of head plain ; highest dorsal spine more than half the length of head in the adult ; 

 lateral line 66—70. 26. vinciguerrce. 



aa. Depth equals length of head. 



c. Maxillary extending to below anterior border of eye ; 10-13 spines on lower border of 



preopercle. Scales 10 or 11-54 to 58-19 or 20. 27. viclanops. 



cc. Maxillary extending a little beyond the margin of the eye; 4-7 spines on the lower limb 



of preopercle ; scales 8-66 to 72-23. 28. altipinnis. 



25. Percichthys trucha (Cuvier & Valenciennes). 



(Plate XXXVI, Fig. 3, and Plate XXXVII, Fig. 2.) 



Perca trucha Cuvier & Valenciennes, Hist. Nat. Poiss. IX, 429, 1833 



(Rio Negro, Chile) ; Guichenot, in Gay, Hist. Chile, Zool. II, 146, 



1848 (Chile) ; id. Atl. Ichthiol. I, v, fig. i, 1854. 

 Perciclithys trucha Girard, Proc. Ac. Nat. Sci. Phila. VII, 1854, p. 197, 



and U. S. Naval and Astronom. Exped. II, 230, 1855 ; Giinther, Cat. 



Fish. Brit. Mus. I, 61 ; Jordan & Eigenmann, Bull. U. S. Fish. Com. 



VIII, 427, 1890 (Santiago and Curico, Chili) ; Boulenger, Mem. Soc. 



Sc. Chile,. IV, 10, 1894; id. Cat. Fish. Brit. Mus. I, 119, 1895; 



