NO. 22 BIRDS FROM CLIPPERTON ISLAND WETMORE 5 



depth of bill at gonydeal angle 10.5-12 (11.3), tarsus 44.8-48 (45.5), 

 middle toe with claw 68.8-78 (73-5). 



Females (14 specimens), wing 385-408 (397), tail 182-198 (189), 

 culmen from base 89.6-103.2 (95.8), depth of bill at gonydeal angle 

 12.3-14.1 (13.3), tarsus 46.8-49.8 (48.2), middle toe with claw 75.8- 



82.7 (79-3)- 



As indicated above, in color this form most closely resembles 

 brczvstcri though the range of the decidedly different ncsiotes inter- 

 venes. Birds from Cocos Island are very slightly paler than those 

 from the Pearl Islands and Gorgona but the difference is too slight to 

 warrant their recognition as distinct. This form has been recorded 

 from the Galapagos Islands but wrongly in my belief. There is one 

 old skin in the National Museum marked "Galapagos Islands," but I 

 consider the locality erroneous. 



Sula leucogastcr leucogastcr (Boddaert) of tropical Atlantic areas, 

 in which male and female are similar, is marked by having the head 

 and neck darker than the back and wings. Sula leucogaster plotus of 

 the central and western tropical Pacific Ocean, which also has the 

 sexes alike, is darker, being the darkest of the races of this bird. 



Family LARIDAE 



STERNA FUSCATA CRISSALIS (Lawrence) 



Socorro Sooty Tern 



Haliplana fuliginosa var. crissalis Lawrence, Proc. Boston Soc. Nat. Hist., 

 vol. 14, 1871 (1872), p. 285 (Socorro Island, Revillagigedo Islands). 



The four specimens, two males and two females, are all adult birds. 

 They are identified to subspecies according to the treatment of 

 Ridgway. 3 



Measurements (in millimeters). — Males, wing 280-282, tail 169- 

 170, culmen from base 43.5-47.5, tarsus 21-22.5. 



Females, wing 274-275, tail 154- 161, culmen from base 40.8-41.1, 

 tarsus 21.3-23.3. 



ANOtiS STOLIDUS RIDGWAYI Anthony 



Socorro Noddy Tern 



Anous stolidus ridgwayi Anthony, Auk, vol. 15, 1898, p. 36 (Socorro Island, 

 Revillagigedo Islands). 



Five males and five females of this interesting bird were obtained, 

 together with two young that are just attaining the plumage of the 

 first fall. 



U. S. Nat. Mus. Bull. 50, pt. 8, 1919, p. 519. 



