202 BROOKLYN INSTITUTE MUSEUM. SCIENCE BULLETIN 2. 6. 



but several of the species are more abundant at some seasons than at 

 others. Or, it is not impossible that the relative abundance or paucity 

 of a given species at any particular season is more apparent than real 

 and is dependent on the habit certain forms have of congregating into 

 great flocks during the dry season. As a group, birds of this family 

 are well known and characteristic of the region. The long purse-like 

 nests of colonies of some of the hang-nests are conspicuous objects in 

 many a landscape. The brilliant plumages of others attract attention, 

 while the vocal powers of certain species are unrivaled among tropical 

 birds. 



Key to the Genera, Species and Subspecies oe Icteridae. 



a. Outstretched feet reaching beyond the end of the tail and claw of hind 

 toe elongated. 



6. Outer tail-feathers largely or entirely white Siurnella magna meridiona- 



lis. 

 b'. Outer tail-feathers not white. 



c. More or less red in plumage of under parts (adult males with throat 



and breast bright scarlet) Leistes militaris. 



c' . No red in plumage of under parts Doiichonyx oryzivorus. 



a'. Outstretched feet falling short of end of the tail and claw of hind toe not 

 elongated. 

 6. Black with iridescent lustre (male) or brown (female). ' 



c. Frontal plumes erect Lampropsar lanagrinus 



guianensis. 

 c'. Frontal plumes not erect. 

 d. Size large, wing more than 150 mm. Neck feathers lengthened 



and expanded - Cassidix oryzivora oryzivora. 



d'. Smaller, wing less than 150 mm. 



e. Length of bill not more than twice its depth; tail square or but 

 slightly rounded. 



/. Size large wing more than 120 mm Mololhrus cahanisi. ^ 



/'. Smaller, wing not more than 120 mm. 



g. Wing not over los mm Molothrus alronitens.* 



g' . Wing more than los mm Molothrus bonariensis 



venezuelensis. 

 e'. Length of bill more than twice its depth. Tail much rounded, 



almost wedge-shaped Holoquiscalus lugubris. 



b'. Not uniformly black or brown, above and below. 



c. Throat uniform with breast and sides and general color of under parts 

 olive green, black or brown. 



d. Entire under parts uniform (black); above, rump bright red Cacicus haemorrhous . 



d'. Under tail-coverts not uniform with breast. 



e. Rump yellow Cacicus cela. 



e'. Rump chestnut. 



/. Body black Osiinops decumanus. 



f. Body olive green Ostinops viridis. 



'The females of Lampropsar lanagrinus resemble the males and are black and slightly glossy. 



^Neck feathers not expanded in females. 



'In the British Museum Catalogue of Birds, XL 1886. 338, this species is recorded from Caracas, 



Venezuela, and Trinidad, so it is not improbable that it will be found later in the delta region of the Orinoco. 



^Hellmayr, Novit. Zool. XIII. 1906. 20, designates the Coast of British Guiana as the type locality. 



The species is found in Trinidad, and Venezuela is included in the habitat given in the Catalogue of Birds, 



British Museum XI. 1886. 337, so we may confidently expect it in the delta region of the Orinoco. 



