386 FISHES OF WESTERN SOUTH AMERICA 
colour adaptations, and most particularly mimetic adaptations. Upholders of 
the theories of protective and warning coloration and of mimicry have often been 
attacked as ‘armchair theorists’ (whereas they have in fact almost invariably been 
first and foremost field naturalists) insufficiently acquainted with modern work in 
genetics, which for some unexplained reason is held to do away with adaptive inter- 
pretations. Dr. Cott has .. . shown that it is they who are the armchair 
GHIUUGS are ae 
It is not my purpose here to enter the debate among worthier contenders, but 
rather to bear witness as to the validity of a natural phenomenon which few men 
have been privileged to see at its best, a phenomenon which even the unclad savage 
has observed, and given his testimony in calling the fish ‘“‘pira-cad-a,’’ or leaf-fish. 
Family X XI: Sciaenidae 
Genus 199: PLAGIOSCION Gill 
Plagioscion Gill, 1861, Proc. Acad. Nat. Sei. Phila., 82; 
Jordan and Eigenmann, 1886 (1889), Rept. U.S. Fish Comm., 380; 
EKigenmann and Eigenmann, 1891, Proc. U. 8. Nat. Mus., XIV, 67; 
EKigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, IIT, 467; 
Kigenmann, 1912, Mem. Carnegie Mus., V, 471. 
Type: Sciaena squamosissima Heckel 
Atlantic drainage from R. Magdalena to La Plata 
Skull not excessively cavernous nor lacking in firmness; preorbital not turgid, 
interorbital space moderate; teeth not villiform, more or less unequal, upper teeth 
in two series, the inner somewhat the larger teeth; pseudobranchiae small; lateral 
line scales the largest and overlapped by the smaller ones. 
493. PLAGIOSCION SQUAMOSISSIMUM (Heckel) 
Sciaena squamosissima Heckel, 1840, Ann. Wiener Mus., I, 432. 
Diplolepis squamosissima Steindachner, 1863, Sitzb. KK. Akad. Wiss. Wien, XLVII, 2; 
Steindachner, 1882 (1883), Denksch. KIx. Akad. Wiss. Wien, XLVI, 1. 
Pachyurus squamosissimus Giinther, 1860, Cat. Fish. Brit. Mus., IT, 526. 
Plagioscion squamosissima Gill, 1861, Proe. Acad. Nat. Sci. Phila., 82; 
Jordan and Eigenmann, 1886 (1889), Rept. U.S. Fish Comm., 381; 
Jordan and Evermann, 1898, Bull. U.S. Nat. Mus., no. 47, IT, 1418; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 468; 
Fowler, 1939 (1940), Proce. Acad. Nat. Sei. Phila., XCI, 280, five, 140-210 mm., Contamana. 
Plagioscion squamosissimum iquitensis Nakashima, 1941, Bol. Mus. Hist. Nat. Lima, V, 68. 
Johnius crouvina Castelnau, 1855, Anim. Amér. Sud, Poiss., 11, pl. v, fig. 1. 
Johnius amazonicus Castelnau, 1855, Anim. Amér. Sud, Poiss., 12, pl. iv, fig. 1. 
Peruvian Amazons to Guiana 
16146, 1, 125 mm., Gosulimacocha, Allen, October, 1920. 
1OL47. 3; , creek near Yurimaguas, Allen, November, 1920. 
16148, 1, 180 mm., Manaos, Allen, December, 1920. 
16149, 1, , Iquitos, R. Nanay, Allen, September, 1920. 
16150, 5, . Iquitos, Amazon, Allen, September, 1920. 
