Vol 'l<m XV ] Clark, Tail-feathers and Coverts. 119 



an unidentified king rail from Brazil showed 6-6. An unidentified 

 coot and a gallinule, also from Brazil, showed 7-6. The position 

 of the coverts is as usual. 



Colymbiformes. A loon showed 10-10, with each covert over 

 its rectrix except 1 . 



Sphenisciformes. A penguin (Spkeniscus) from Chili showed 

 10-10, each covert over its rectrix. There is great difficulty in 

 both the loon and the penguin in distinguishing the major from the 

 other coverts, so densely are the feathers crowded on the pygidium. 



Procellariformes. In Procellaria, Fulmarus and Daption 

 the number of coverts is the same as the number of tail-feathers, 

 6-6; in one petrel, I found only 5 coverts on one side. But in 

 Ossifraga (8-10) and Diomedia (6-8 or 9) the coverts are distinctly 

 more numerous than the rectrices. The extra coverts are beyond 

 the outer rectrices. 



Alciformes. In Uria (= Cepphus) the formula is 6-8 or 9, 

 and one of the extra coverts may be at the inner end of the series; 

 it is apparently a supernumerary covert in the strictest sense, as it is 

 probably not really homologous with the other major coverts; 

 this is indicated by its small size and its position above rectrix 1 

 on its inner side. The coverts are seldom over their rectrices, 

 though 1 and 2 generally are; covert 7 is over rectrix 6, but 3, 4, 5 

 and 6 lie between rectrices. The third or fourth covert is longest, 



2 and 1 being decidedly smaller. In Fratercula, the formula is 

 8-9 and the coverts are almost or quite over their respective rec- 

 trices; 9 is outside rectrix 8. The third or fourth covert is clearly 

 longest. 



Lariformes. In Sterna, Rynchops and a few gulls, the formula 

 is 6-6 but in two large unidentified gulls, it was 6-7 or 6-8; the 

 outer coverts are small and might easily be overlooked. In 

 most gulls covert 1 is a little smaller than 2. 



Charadriiformes.— In Jacana, the formula is 5-5 but in Are- 

 naria, Mgialitis, Numenius, Bartramia, Calidris and Pelidna, it is 

 6-6. I regret greatly I could examine none of the shore-birds 

 having more than 12 rectrices. 



Gruiformes. In Grus americana, the arrangement is 6-6 and 

 each covert is over its own rectrix. Covert 1 is the smallest and 



3 is the largest, 2, 4, 5 and 6 being intermediate. 



