98 



PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxi. 



mann it inhabits fresh water, but that he knows of it only in the mouth 

 of rivers, in brackish water; for example, the Rio Negro in northern 

 Patagonia. 



We have 24: specimens that we identify as tnis species from lakes 

 Nahuel Huapi and Traf ul and from Nirihuahu, tributary' of liio Limaj^ 



Our specimens range in total length from 1.43 to 13.5 inches, agree- 

 ing very well with Jen3ms' description and ligure. 



The following table of proportional measurements indicates the 

 range of variation in specimens of the various sizes: 



Proportional measurements of Basilichthys microlepidotus. 



Family MUGILID^. 



37- MUGIL BRASILIENSIS Agassiz. 

 LISA. 



Mugil brasiliensis Agassiz in Spix, Pise. Brasil., 1829, p. 134, pi. lxxii, Atlantic 

 Ocean.— Berg, Anal. Mus. Nac. Buenos Aires, IV (2d ser., I), 1895, p. 31 

 (Costa patagonica; Bahia Blanca, Mar del Plata, Cabo de San Antonio; Mon- 

 tevideo ; Maldonado ) . 



3Iugil liza, Perugia, Ann. Mus. Civ. Stor. Nat. Genova, 2d ser., X (XXX), 

 1890-91, p. 622 (Montevideo). 



Berg has shown that this species exhibits considerable variation in 

 form according to the size of the fish, and in color according to the 

 character of the water inhabited. It enters brackish and fresh water. 



The following notes taken from the 4 specimens representing this 

 species from Rio de la Plata in our collection show some variation in 

 proportional measurements in examples of about the same size: 



(1) Total length 12 inches; length without caudal 9.67 inches. Head 

 3.85 in length without caudal; interorbital 2.10 in head; D. IV-8; A. 

 Ill, 8; scales 36 or 37, -12. 



(2) Total length 13 inches; length without caudal 11 inches. Head 

 4.09; interobital 1.79; D. IY-8; A. Ill, 8; scales 35, -12. 



(3) Total length 13 inches; length without caudal 10.5. Head 4; 

 interorbital 1.90; D. IV-8; A. Ill, 8; scales 35, -12. 



(4) Total length 13.5 inches; length without caudal 11. Head 4.09; 

 interobital 1.95; D. IV-8; A. Ill, 8; scales 35, -12. 



