22 BUULETIN 133, UNITED STATES NATIONAL MUSEUM 



the mountain slopes in little bands, traveling down toward the 

 plains where they passed on northward. With heavy storms in the 

 higher reaches, these movements become more pronounced and at 

 times include hill inhabiting species that temporarily pass down 

 to the warmer lowlands until the stress of weather has passed. 



It was interesting also to observe the migrational movements of 

 a form of the monarch butterfly {Anosia erippits) that wintered 

 in numbers in the Chaco, and in spring flew southward to spread 

 over the pampas. 



ANNOTATED LIST OF BIRDS 



The following account consists of an annotated list of the species 

 of birds collected, with observations on a few of which no specimens 

 were taken. Measurements, made in millimeters, have been taken 

 by the method usual among present day American ornithologists. 

 The wing measurement is the chord of the distance from the bend 

 of the wing (the metacarpal or wrist joint) to the tip of the longest 

 primary taken with dividers except in large birds where the measure- 

 ment is made with a straight rule, but without flattening the wing. 

 The length of tail, measured with dividers, is the distance from the 

 base of the median rectrices on the uropygium to the tips of the 

 longest tail feathers. The culmen has been measured from the base 

 in all cases except where (as in parrots) it is specified as taken from 

 the cere, etc. The distance, measured with dividers, is taken in a 

 straight line from the basal point to the extreme tip. The tarsal 

 length, likewise taken with dividers, is secured by placing one point 

 of the instrument at the upper end of the tarsus on its posterior 

 side, and the other at the end of the middle trochlea of the meta- 

 tarsus. 



With shifts in generic names, so common in our modern nomen- 

 clature, at times a change is required in the current designation for 

 a family. Current family names have been derived from the appel- 

 lation of some genus considered as typical of the group concerned, 

 in the main from the oldest genus name in the family. Where this 

 genus name has been changed through the application of the law of 

 priority in publication, type fixation, or other cause, change in the 

 family name necessarily follows. Certain ornithologists (mainly in 

 England) are advocating derivation of a new family name from the 

 next oldest generic appellation. This, however, may cause confusion 

 since it may result in shifting the tjq^e genus from a group that 

 has been held typical of the family concerned, to one that is aberrant 

 or possibly even to a genus of doubtful allocation. The confusion 

 that may arise is easily evident. It seems preferable to allow the 

 same generic group to remain as typical of the family regardless of 

 change in its appellation; in other words, to allow the family name 



