NO, 11 GARTH : DISTRIBUTION STUDIES OF BRACHYURA 605 



may be moving at differing rates of speed and in opposing directions in 

 these channels simultaneously. It is further probable that water flowing 

 through these channels may undergo a seasonal reversal of direction in 

 response to movements of large water masses in the greater Pacific area. 

 However, since each of the five Allan Hancock Expeditions to the 

 Galapagos was made in the months of December, January, and February, 

 observations of conditions during these months only can be given. 



As shown by the accompanying Chart HI, a body of warm water, A, 

 flowing southeastward between northern Albemarle and James Islands, 

 meets a current of cold water, B, flowing northwest between southern 

 Albemarle and Indefatigable Islands, and is deflected to the east off 

 Jervis and Duncan Island, E, along the north shore of Indefatigable 

 Island, to join the warm water streaming down the east side of James 

 Island, which has met cold current C somewhere between James and 

 Tower Islands, as at F. Observations in this connection are ( 1 ) the 

 drifting of the expedition cruiser Velero III in a current too strong to 

 permit anchoring, along the north shore of Duncan Island in the direction 

 of Indefatigable, (2) the conflict of two currents coming from the south 

 around each side of Charles Island while dredging was being attempted 

 at G, (3) the casting of the survivors of the sloop Dinamita, becalmed 

 while crossing from Indefatigable to Chatham Island, upon Bindloe 

 Island, nearly 100 miles northwestward, and (4) the driving of an 

 Ecuadorean fishing vessel out of Academy Bay towards the Gordon Rocks, 

 opposite C. 



Evidence of a difference of as much as 20° F. in surface temperature 

 between the cooler current coming from the southeast and warmer current 

 from the northwest was obtained in January, 1932, when 66° F. was 

 recorded on the west side of Albemarle Island and 86° F. on the east, the 

 former corresponding to surface temperatures of Coastal Peru, the latter 

 to that of Cocos Island, in the Bay of Panama. At the northern tip of 

 Albemarle, where these currents met at D, an extensive current rip was 

 noted in December, 1934. At Tagus Cove that year overcoats were worn 

 for comfort, while at Cartago Bay, on the eastern side of the Island, sum- 

 mer clothing was in order. Galapagos penguins were seen at both Tagus 

 Cove and Duncan Island, while at Cartago Bay the manta ray {Manta 

 birostris) and the sea snake (Pelamis platurus) , both characteristic of 

 warm tropical seas, were observed. 



Taking Hood Island as a hypothetical starting point, a scheme of water 

 circulation based upon the observations just given would account for the 

 present known distribution of Peruvian species in the Galapagos Islands. 



