36 R. W. Shufeldt 



As my figures on the plates are of natural size, and present this inner 

 trochlear process of the right tai"so-metatarsus of Diatryma gigantea 

 from several points of view, it obviates the necessity of writing out 

 any special description of it. Moreover, the description given under 

 the aforesaid several figures is very full, rendering it still less neces- 

 sary to enlarge upon it here. I may say, however, that in the tarso- 

 metatarsus of the vast majority of birds there is, at the distal end, an 

 oval foramen which transmits the anterior tibial artery, as it passes 

 to the sole of the foot to become the plantar artery. This foramen is 

 just above the valley between the outer and the middle trochlear 

 processes, and consequently on the outer side of the bone. It does 

 not form until complete ossification takes place in the adult, while in 

 some birds it remains as a "notch" throughout life, merely deepening 

 the valley between the middle and outer trochlear processes. It is 

 entirely absent in the Moas and in the Ostriches, in which birds the 

 anterior tibial artery apparently finds its way to the sole of the foot 

 by simply passing between the aforesaid processes. It is well marked 

 and thoroughly indi\adualized in all true gallinaceous birds, and in 

 Figures 69 and 70, Plate IX, I invite attention to it in the tarso- 

 metatarsus of the Cock of the domesticated Gallus, there introduced 

 to compare with my partial restoration of the distal extremity of the 

 right tarso-metatarsus of Diatryma gigantea of Cope, — a much smaller 

 species than D. ajax, elsewhere described by me. 



Now, in the outer trochlea of Diatryma gigantea {Tynpe U. S. Nat. 

 Mus.), in the same locality where this anterior tibial foramen is found, 

 I find a smooth, hemicylindrical, antero-posterior groove, which is, 

 beyond all question, the distal half of the interior surface of the outer 

 side of the foramen above described. It has an antero-posterior 

 length of 1.5 centimeters, and a transverse diameter of 6 millimeters. 

 There appears to be an indication of its opposite surface in the similar 

 locaUty, on the outer aspect of the superior part of the middle trochlear 

 projection; but the two trochlese do not come accurately together 

 there. In fact, while there is a shallow, antero-posterior groove in 

 evidence, its margins have not the appearance of recent fracture, 

 which leads me to beheve that the trochleae were long separated before 

 their discovery — perhaps for many thousands of years. The inter- 

 esting fact here is that a thoroughly differentiated anterior tibial 

 foramen was present in the distal end of the tarso-metatarsus of Dia- 

 tryma gigantea and probably in D. ajax, while it was entirely absent 

 in Struthio and Dinornis maximus, and probably in other Moas. 



