1918.] Under Wing-Coverts of Birds. 571 



reversed feather at the wrist-joint, found in the two examples 

 of Clicptura, is not placed iu line with either portion of the 

 main series, and does not appear to he a continuation of the 

 coverts on the cubitus, like the similar small feather noted 

 in some Kingfishers, etc. ; but it appears to be rather the 

 single remaining feather of an obsolete row of median 

 coverts. So we must consider the whole series of reversed 

 coverts in the Swifts to be the major coverts, as in the 

 Cuckoos. 



The Passeriformes.—^ow all the birds examined with 

 regard to their reversed under covens have been reviewed, 

 excepting the Passenformts. The large number of these 

 examined (over four hundred examples belonging to 134 

 species) makes it necessary here to use a more concise 

 method of treatment than with the other orders, and give 

 first the general characters and afterwards particular modi- 

 fications. This is, moreover, easy to do with the Passeri- 

 formes, on account of the great uniformity in their reversed 

 under coverts, and the slight nature of such modifications 

 as occur. 



First, then, is given a general description that applies to 

 all the Passeriform birds examined, without exception, and 

 will not be repeated: — 



Major under coverts present on the manus, ten in number, 

 or often less, but never more; not present on the cubitus as 

 full-sized or functional coverts, but often found as small 

 or rudimentary feathers, as in some of the Kingfishers. 

 These rudimentary major under coverts in Passeriform birds 

 are often larger at the distal end of the cubitus, next to the 

 manus, and the first manual major under covert is often 

 reduced in size ; so that there is a gradual transition from 

 the full-sized ones on the manus to the rudimentarv ones 

 on the cubitus. The major under coverts are more closely 

 joined to the remiges in this order than in any other birds. 

 The oveilap is always conforming throughout the series. 



Median under coverts present on the cubitus, with an 

 extra one at the carpal joint, making the number of the full 

 series ten ; but one or two may be wanting at the proximal 



