100 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxi. 



quantities. He calls attention to the fact that the description by 

 Jonyns has been corrected and added to by Steindachner, Liitken, and 

 Perugia, and that the black spot under the pectoral is variable in 

 intensity and extent, and is occasional!}' absent. 



Regarding the size attained 1)}^ this i<pecies, Berg says that he saw 

 one measured at Montevideo that was 45 cm. [over 18 inches] long 

 without the tail, and 18 cm. in height. 



Our collection contains 5 specimens 11.25 to 16.5 inches in total 

 length, from Mar del Plata. The following notes were taken from our 

 largest example: 



Total length from tip of lower jaw to tip of caudal 16.5 inches; 

 length to fork of caudal 14.75 inches, and to Imse of caudal 14; depth 

 2.33 in length without caudal; I). I-I-I-I-I-I, 32, the longest soft 

 rays or anterior lobe, 1.46 in head; A. I-I, 32, the longest rays or 

 anterior lobe, 2.03 in head; head from tip of lower jaw to gill-opening, 

 3.92 in length without caudal; eye 6.33 in head; snout 4.07; distance 

 from tip of snout to posterior extremity of maxillary a little less than 

 7 in head; width of posterior extremity of maxillary 1.4 in snout. 



The soft dorsals of our other specimens contain 33, 39, 34, and 35 

 rays, respectively. 



Berg gives the vertical fin counts as D. VII, 1, 33-34 (rara V. 35-1, 

 36); A. II, I, 34-36 (II, I, 37). 



Family SERRANID/E. 



40. PERCICHTHYS TRUCHA (Cuvier and Valenciennes). 

 TRUCHA. 



Perca trucJia Cuvier and Valenciennes, Hist. Nat. Poiss., IX, 1844, p. 429, Rio 



Negro, Patagonia. 

 Perca hrris Jenyns, Zool. Voy. Beagle, Pt. 4, Fish, 1842, p. 122, pi. i, Santa Cruz 



River, Patagonia. 



Cuvier and Valenciennes say that this fish seems to abound in the 

 fresh waters, neither ascending from nor descending to the sea; that 

 the inhabitants call it "trucha," which is the Spanish name for trout. 

 It is also said to be "delicate eating" and highly esteemed. It attains 

 a foot in length. 



Mr. Titcomb found the trucha along with the pejerrey in the Rio 

 Negro in south latitude 39°, but no spawning fish were among them. 

 He found them together at several places also in the Rio Limay and 

 its tributaries early in November. Late in that month they were 

 found spawning in Lake Nahuel Huapi. They seemed to be abundant 

 both in the Rio Limay and in tributaries to the lake, which they 

 ascend at spawning time, w^hich appears to be in December, as Mr. 

 Titcomb obtained spawning fish December 13. 



The largest trucha seen by Mr. Titcomb was taken in Lake Traful, 

 and measured 48 cm. long. 



