10 BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



from Peni range northward of that country. On the other hand, it 

 has been shown that comparatively few range beyond the southern 

 boundary of Peru. It perhaps is significant, also, that the abundant 

 family Nototheniidae of the South Temperate coasts of America 

 has not to date been listed from Peru. Neither are the Gadidae, 

 Macrouridae, and Zoarchidae, all found in Chile, represented among 

 the Peruvian fishes. These facts seem to show that the shore fishes 

 of Peru are predominantly tropical in character. 



As Peru lies almost wholly between latitudes 3° and 17° S., a 

 tropical fish fauna would be expected there. However, winds and 

 currents have been said to affect profoundly the temperature of the 

 water, at least along the greater part of the coast, and near the shore. 

 This matter will not be treated here, as it has been discussed at 

 considerable length in the report of the Mission (1943, pp. 200-232), 

 and prior to that by R. E. Coker (1910), R. C. Murphy (1923), and 

 others. According to the more recent data, the cold water seems to 

 be near shore only and is caused by an upwelling of cold water (at 

 least according to Dr. Murphy) , which in turn is caused by winds and 

 currents. Whatever the extent of the cold water may be along the 

 shore, it is not great enough to exclude all tropical fishes. 



The present study, then, shows that although the fish fauna of 

 Peru is predominantly tropical, a considerable number of warm- 

 water-inhabiting species, known from Central America and northern 

 Peru, do not range into southern Peru. It was stated by Nichols 

 and Murphy (1922, p. 513) that the Peruvian fish fauna has its 

 "closest faunal affinities with the Californias" and that the "shore-fish 

 fauna is subtropical or temperate rather than tropical m character." 

 There are, indeed, certain afiinities between these faanas, for it has 

 been shown that about 75 of the Peruvian species occur also in and 

 beyond Baja California. However, all except 8 of these are recorded 

 from Central America also. It seems correct to say, in the light of 

 farther studies, that the similarity of the fish faunas of Peru (exclusive 

 of the extreme northern part of that country, which is strictlj^ tropical) 

 and Baja California consists chiefly in the support of those tropical 

 species which tolerate a somewhat lower temperature than some of 

 their associates of Central America and northern South America. 

 In that sense the fishes of Peru, as well as those of Baja California, 

 perhaps may be considered "subtropical." 



DEFINITIONS OF TECHNICAL TERMS USED IN THE TEXT ' 



Adipose fin. — A fleshy fin on the back, behind the dorsal fin, without rays, occa- 

 sionally with a spine, present in most catfishes, lizardfishes, etc. 

 Articulate. — Jointed; said of soft rays bearing articulations. 



» The definitions are intended to define the use of the terms in Ichthyology only. The reader is referred 

 to figure 3 on page 12 for additional terms used in describing external structures of fishes. 



