1^0.4.] SHUFELDT ON THE OSTEOLOGY OF SPEOTYTO. 113 



ary of tlio Lead makes an angle of a good 45° with this line, so that 

 with these facts in view we can hardly assert in the case of the species 

 before us, as do some authors on comparative anatomy in describing 

 this bone in generalj that the axis of the head of the femur is either 

 nearly at right angles with or is sessile with the sliaft. It would ap- 

 pear, though, that it has quite as much of a neck to boast of as the ana- 

 tomical neck of humerus or the neck of the scapula in works on hu- 

 man anatomy. The shaft throughout its length, until it begins to ap- 

 proach the distal condyles, where it is subcompressed and expanded 

 antero-posteriorly, is nearly cylindrical, bent slightly backwards at its 

 lower end, and offers for examination merely the iutermuscuhir ridges, 

 with the linea aspera, feebly marked, and the nutrient foramen, all of 

 which maintain their usual positions on the bone. At the distal ex- 

 tremity the rotular canal, the intercondyloid notch, and the popliteal 

 fossa are all strongly produced, giving due prominence to the condyles, 

 internal and external, between which they form the dividing tract. The 

 external and lower condyle is divided in two by a vertical excavation, 

 deepest above. Of the two facets thus formed, the inner articulates 

 with the tibia, the outer with the head of the fibula. The external sur- 

 face of this condyle is flat and continuous with the shaft. The inner 

 condyle, broad posteriorly, has a slight depression in the surface that 

 bounds it on the tibial side, and as a rule the usual sites for ligamentous 

 attachments about this extremity are at best but feebly represented. 

 The 2mtella, encased in the tendon of the quadriceps femoris, is situated 

 about 3 millimetres above the rotular crest of the tibia, anteriorly, hav- 

 ing the form of an oblate hemispheroid with its base directed upwards, 

 the long diameter of which measures 3.5 millimetres. The tibia is the 

 longest bone in this bird's skeleton, and at the same time, taking this 

 length into consideration, the least curved or bent along the shaft; it 

 has, however, a slight and just appreciable gradual curvature forwards 

 that is most apparent about the junction of middle and upper thirds. 

 Its average length, measured on the inside, is G.7 centimetres ; its ex- 

 tremities being expanded for articulation, above with the fermur, below 

 with the tarso-metatarsus. These expansions are of about equal dimen- 

 sions, though ditfering vastly in form, in this respect being unlike some 

 of the diurnal Baptorcs, in which the distal condyles constitute the 

 smaller end of the bone. 



Among the most imjDortant points presented for examination about 

 the head is the articular surface that crowns it above for the condyles 

 of the femur. This is subquadrate in form, uneven, highest at the in- 

 ner and anterior angle, sloping gradually to the opposite one, bounded 

 almost entirely around by a raised margin, that is most feebly devel- 

 oped posteriorly, and at a point anterior to the head of the fibula, where 

 it is absent. In front this border may be nominated the rotular or epi- 

 cnemial ridge, though it is no more prominent there than at any other 

 point, but in many birds it is so produced as to produce a process of 

 8gb 



