144 BULLETIN UNITED STATES GEOLOGICAL SUBVEY. [Tol.Yl, 



and articular facet for the metacarpal to which it belongs. It bears be- 

 low another, and the smallest, phalanx of the hand, a little, free, sharp- 

 pointed finger, markedly compressed, that completes the skeletal bird- 

 arm distally, it being the ultimate segment. 



The third metacariDal, termed annularis, a slender, ribbon-like bone, 

 fast above and below to medius, and extending slightly beyond it, also- 

 articulates distally with another free phalanx, of the general character 

 as the index digit and the ultimate joint of the mid-metacari3al, although 

 it is longer than either of them. Measuring along the anterior aspect, 

 from the summit of mid-metacarpal to the point of its last phalanx, we' 

 find the manus in EremopMla to average 2.6 centimetres. 



This, the pectoral Hmb, as we have endeavored to picture it in this 

 Lark, with its brachium, anti-brachium, and pinion in proportionate 

 equipoise as to length of segments, with its various bones smooth, 

 markedly straight, and devoid of those evidences of being acted upon 

 by powerful muscles, would require but a single glance from the student 

 of avian skeletology to pronounce it as belonging to a bird possessed 

 of a flight barely mediocral in rapidity and power. 



Of the pelvic limh— (PI lY, Figs. 22, 39, 40, 42, 44, and 46).— The inner 

 aspect of the upper extremity of the femur presents the usual globular 

 head for articulation with the cotyloid ring of the pelvis. It is nearly 

 sessile with the shaft, the neck amounting to almost nil. A shallow and 

 inconspicuous excavation occurs on the head for the insertion of the 

 ligamentum teres. The articular surface that originates with this hem- 

 ispherical j)rotuberance extends outwards over the summit of the bone, 

 constantly spreading, until limited by the trochanterian ridge, in a 

 plane with the outer aspect of the shaft ; it occupies a slightly higher 

 level than the head, and it is opposed to the anti-trochanter in the articu- 

 lated skeleton. 



Anteriorly the trochanterian ridge and line are quite prominent, ex- 

 tending a short distance down the shaft, to be lost on the general surface; 

 posteriorly it projects outwards horizontally from the articular surface, 

 over a shallow concavity that is found immediately below, that presents 

 at its base a circular foramen that leads to the hollow shaft, and is 

 probably pneumatic, though the femur of this bird does not have the 

 appearance of a bone possessed of pneumaticity ; the orifice, if nutrient, 

 is certainly situated in an unusual i^lace, though we must confess that a 

 careful search over the entire shaft with a powerful lens failed to reveal 

 any other opening. The trochanter minor is not represented. 



The shaft, for the greater part of its extent, is cjdindrical, with a clean 

 superficies, undivided by any intermuscular ridges or lines, or, if so, 

 very faintly, and decidedly convex forwards. 



The distal extremity of the femur enters largely into the knee-joint, and 

 is more bulky than the proximal extremity of the bone. It is directed 

 backwards, and, as usual, is divided by an antero-posterior shallow in- 

 tercondyloid notch, which is continued up the shaft anteriorly, as the 



