NO. 11 GARTH : DISTRIBUTION STUDIES OF BRACHYURA 607 



The Peruvian Current, with its coastal and oceanic subdivisions, is a 

 portion of the largest ocean current in the world, the Antarctic 

 Circumpolar Current, deflected northward by the tip of South America. 

 It carries polar water with little change in temperature from southern 

 Chile almost to the Equator. An observed surface temperature is 66° F. 

 in the Galapagos Islands, 35.00 o/oo ^n average saline content. Unlike 

 the Nino Current, the Peruvian Current is permanent and undirectional, 

 unvarying except as it may be seasonally deflected away from the South 

 American mainland north of Latitude 12° S. 



A seasonal and cyclical analysis of ocean currents off the northwest 

 coast of South America is given by Schott (1931), from whose work the 

 accompanying three charts are taken. Chart V shows normal current 

 displacement during August and September, which are winter months 

 south of the Equator. During these months the Galapagos Islands are 

 completely surrounded by cold water, the coldest axis of the Peruvian 

 Current passing just south of the islands of Charles and Hood. 



Chart VI shows the normal current displacement in February and 

 March, the summer season south of the Equator. At this season the body 

 of warm water, represented by diagonal striping, moves southward to in- 

 clude the islands of Culpepper and Wenman, almost reaching the tip of 

 Albemarle Island. According to observations of the Hancock Expedition 

 members, this warm water does reach Albemarle Point and inundates the 

 channel betv/een Albemarle and James, as previously related. 



Chart VII shows an unusual disturbance which took place in 1891. In 

 that year the belt of warm water was pushed southward past the 

 Galapagos Islands to Callao, Peru, and beyond, seriously upsetting the 

 meteorological and biological equilibria. The arid coasts of southern 

 Ecuador and Peru were deluged by tropical rainfall. Millions of guano- 

 producing birds were destroyed in the Peruvian coastal islands. The 

 important fact to be noted is that the Galapagos Islands were completely 

 immersed in warm equatorial waters. Such an occurrence takes place in 

 milder proportions every seven years, according to Murphy (1936), with 

 serious disturbances about every thirty-fourth year. Murphy presents 

 substantial proof that these serious disturbances of 1891 and 1925 were 

 not caused by the Nino current, but were invasions of the southern hemi- 

 sphere by the Equatorial Countercurrent {op. cit., p. 103). Schott 

 {op. cit.) records twelve such disturbances since 1791, the most serious 

 known being that of 1925. It will be recalled that the single record of a 

 Gulf of California species of Brachyura on the extreme southern island 

 of Hood, that of Leptodius occidentalisj was in this year. Thus the 



