ART. 5. FOSSIL BIRDS FROM ARIZONA WETMORE. 9 



Miller as Pavo calif ornicus? Later, when an abundance of additional 

 material became available Doctor Miller,* in an excellent account of 

 his further studies of the species, proposed for it the generic name of 

 Para pavo, and compared it with Agriocharis. His careful and lucid 

 account of the characters of this bird leave nothing to be added in 

 the way of description. 



From examination of the tarsal bone it is my opinion that Para- 

 pavo is a meleagrine form intermediate in its characters between 

 modern Meleagrls and Agriocharis. The three, though evidently 

 ■closely allied, offer distinctions of generic value. The characters 

 marking adult males ma}^ be conveniently shown in form of a key. 



«\ Distance from lower margin of spur core to distal end of middle trochlea 



50 mm. or more ; the two lateral trochleae less produced posteriorly 



beyond axis of shaft ; bone stronger, heavier. 



W. Intermediate hypotarsal ridge absent or but slightly developed ; inner 



border of middle trochlea produced proximally on posterior face as a 



sharp ridge that extends upward toward shaft, beyond upper end of 



groove on face of trochlea ; head of bone proportionately broader and 



heavier. 



Meleagris. 

 &'. Intermediate hypotarsal ridge well developed ; inner border of middle 

 trochlea cut away on posterior face, not produced in a proximally ex- 

 tended ridge; head of bone proportionately more slender. 



Parapavo. 

 «^ Distance from lower margin of spur core to distal end of middle trochlea 

 45 mm. or less ; the two lateral trochlea more produced posteriorly 

 beyond axis of shaft ; bone slighter, more slender. 



Agriocharis. 



It will be noted that Pojrapavo has been grouped above with 

 Meleagris. Six characters have been found in which these three 

 genera offer points of difference. In three of these Parapavo agrees 

 with Meleagris., and in three with Agriocharis. One character in 

 each group is based on size and may be disregarded as of slight im- 

 portant. Of the others the two that unite Parapavo and Meleagris., 

 that is, elevation of spur core and position of the lateral trochlea with 

 regard to the shaft seem of greater weight than the two that join 

 Parapavo to Agriocharis., namely the presence of an intermediate 

 hypotarsal ridge and the conformation of the inner border of the 

 middle trochlea. The first two are deemed of greater importance 

 since they are established when the tarsal elements coalesce during 

 development of the young individual, while the others, less primi- 

 tive, are more subject to modification through subsequent stress or 

 strain as the bird gains in age. 



The two species of modern peacocks, Pavo muticus and P. 

 cristatus, members of the family Phasianidae, and the two modern 



3 Univ. Calif., Publ., Bull. Dept. Geol.. vol. vi, August, 1900, p. 285. 

 * Idem, vol. 9, Mar, 10, 1916, pp. 89-96. 



