752 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



ENDOMYCHURA HYPOLEUCA (Xantus). 



XANTUS'S MUURELET. 



Adults in breeding plumage (sexes alike). — Upper parts, including 

 whole of loral and upper half of auricular regions, slate color or deep 

 slate-gray, the scapulars, interscapulas, and wing-coverts slate- 

 blackish centrally, the primaries and primary coverts dull blackish 

 slate narrowly margined with slate color; a narrow white crescentic 

 mark beneath lower eyelid ; entire imder parts, except outer portion 

 of sides and flanks, immaculate white; outer portion of sides and 

 flanks slate-gray, some of the feathers tipped with white; under 

 wing-coverts immaculate white; inner webs of primaries grayish 

 white passing into gray distally and toward shafts; bill black, the 

 basal portion of mandible pale bluish in life ; iris dark bro\Mi ; inner 

 side of tarsi and upper surface of toes and webs pale blue (in hfe), 

 the outer side of tarsi and under side of feet dusky. 



Winter plumage? — Similar to the summer plumage, but with white 

 on sides of head involving most of the loral, suborbital, and 

 auricular regions. 



Downy young. — Upper parts uniform black; under parts, including 

 malar and suborbital regions, immaculate pure white; a flank-patch 

 of grayish black or dusky gray, confluent with black of rump; thighs 

 blackish. 



Adult male. — Wing, 118.1; exposed culmen, 19; tarsus, 24. 1.'' 



Adult female.— Wmg, 113-127.5 (118.3); tail, 30-33 (31.3); 

 exposed cuhnen, 15.2-23 (18); tarsus, 22-25 (23.8); middle toe, 

 21.5-24.5 (22.7).^ 



Coasts and islands of southern Oahfornia and Lower California, 

 from Monterey Bay to Cape San Lucas; *= breeding (at least formerly) 

 on Santa Barbara and Los Coronados islands. 



•Brachyrhamphus hypoleucus Xantus, Proc. Ac. Nat. Sci. Phila., xi, Nov., 1859, 

 299 (Cape San Lucas, Lower California; coll. U. S. Nat. Mus.). — Baird, 

 Proc. Ac. Nat. Sci. Piiila., xi, 1859, 306 (Cape San Lucas; crit.). — Elliot, 

 lUustr. New and Unfig. N. Am. Birds, pt. 8, 1867, (vol. ii), pi. 72.— Coues, 

 Proc. Ac. Nat. Sci. Phila., 1868, 64 (monogr.); Check List, 2d ed., 1882, 

 no. 868.— RiDGWAY, Proc. U. S. Nat. Mus., iii, 1880, 211 (Cat. N. Am. Birds, 

 no. 757); v, 1883, 534, footnote (Cape San Lucas and San Jose del Cabo); 

 Nom. N. Am. Birds, 1881, no. 757.— Goss, Auk, i, 1884, 396 (at sea near 

 San Diego, California, May 20, 1884; measurements, etc.). 

 B[rachyrhamphus] hypoleucus Coues, Key N. Am. Birds, 2d ed., 1884, 813. 



o One specimen. 



b Six specimens. 



c Definite localities are: San Diego, Jan. 27; Monterey Bay (Sept. 2 to Apr. 25; 

 July 29, several pairs); between San Pedro and Santa Catalina Island; near Santa 

 Barbara; Santa Barbara Island; Santa Cruz Island; Los Coronados Islands (May 15, 

 20), Guadalupe Island, San Benito Island, San Jose del Cabo, and Cape San Lucae. 



