OSTEOLOGY OF LARID^. 601 



witl] smooth, thickened, elevated edges, and a prominent overhanging articulating facet 

 on its supeio-xjosterior border, for the trochanter major of the femur to rest upon. 



Femur. — This bone is exceediuglv short, but quite straight (differing greatly in this 

 respect from I'uffinus), and only moderately stout. The shaft is nearly cylindrical, in- 

 clining above slightly inward toward the median line of the body, its lower extremity 

 presenting somewhat backward. Superiorly the bone expands into a large, thick, stout 

 trochanter, much elevated, and with a well-marked margin, which rises high above, 

 curves toward and slightly overhangs the head of the bone. From the inner side of this 

 trochanter the head projects directlj' inward ; there is no cor«striction of the ''neck," 

 except To a very slight degree below ; above, the articular hearl of the bone is directly 

 continuous with a smooth concavo-convex space between it and the crest of the troch- 

 anter. The shape of the articulating surface is such that it perujits the head to siidc 

 but slightly into the acetabular ring, the chief weight of the bird being borne by the 

 superior aspect of the trochanteric prominence, which is accurately coaptated to tho 

 overhanging abutment which projects from the superior margin of the acetabulum. 

 The fossa for the ligamentum teres is directly on the superior aspect of the head. The 

 whole outer aspect of the trochanter is rough for tendinous and ligamentous attach- 

 ments. 



The femoral condyles differ markedly in size and shai^e. The outer is the longest, 

 and very much the largest. The two are widely separated by a deep groove, which 

 runs up a considerable distance on the anterior face of the bone, and on the posterior 

 is continuous with the popliteal depression. The outer projects much the furthest out- 

 ward, downward, and especially backward. Its face, posteriorly, is divided by a longi- 

 tudinal groove. This groove receives the autero-posteriorly elongated head of the 

 fibula, forming the chief part of the femoro-tibular articulation ; while the ridge which 

 bounds the groove internally dips down into the space between the heads of the fibula 

 and tibia. The inner condyle has a broad, flat, oval face, which is applied directly to 

 the plane liead of the tibia. 



TLe two tibial crests are peculiar in shape and situation. The anterior of these is 

 short, but very high, rising as a thin, vertical lamina to quite an apex ; being trian- 

 gular, and nearly as high as long at the base. It is exceedingly thin, its sides perfectly 

 plane and vertical. The other crest is at right angles with the first ; looking directly 

 outward instead of forward, and having its side instead of base applied to the bone. 

 Its base is nearly identical with the base of the first, but is at right angles with it. 

 The superior margins of these crests unite at their termination, and both rise above 

 the level of the head of the bone. The lateral crest being transverse to tho line of 

 motion in the joint, forms a protecting wall or face in front of the joint, between the 

 margins of which, and the head of the bone proper, there is a gentle and rc-^gulnr con- 

 cavity. The inner edge of the true head of the bone is directly' continuous with tho 

 base of the anterior crest ; but between the outer edge and the extremity of the lateral 

 crest there is a deep notch. 



The head of the fibula is on the same plane with, and at the inner edge of, the head 

 of the tibia. It is narrowly oval, almost crescentic, its long axis antero-posterior. It 

 is only ligamentously connected with the tibia ; below, after a short space, it becomes 

 more or less completely anchylosed ; becomes again detached from the tibia, to finally 

 disappear a littlo below tlje middle of the bone. 



The tibial condyles, as usual, project further forward than backward. They are 

 much of the same size and shape, and on the same plane; the inner, however, is less 

 stout and projects more, both inward and forward. Posteriorly the condyles subside 

 into two acute ridges, having between them a smooth, laterally concave surface, over 

 which pass the extensor tendons. Above and between the two condyles on the anterior 

 surface of the bone, there is the ordinary fossa, parti illy converted by a bridge of bono 

 into a canal for th(i confinement of the tendon of tiic extensor digitorum. 



The metatarsus is modera'ely long, contained 14 times in the tibia-. Its shaft is com- 

 pressed into a pretty regular (|uadrilateral shape, the lateral sides, however, remaining 

 a little convex. The tendons that go to the toes are mostly aggregated upon the ante- 

 rior anil posterior aspects of the bone. Above, the bono expands into a large, irregu- 

 lar head, widened laterally for the reception of the two condyles, and posteriorly by 

 a short, high crest, into which is inserted the gastrocnemial tendon. This crest has also 

 several longitudinal grooves, deep and distinct, which conduct tendons to the toes. 

 The facets for tlu! reception of the tibial condyles are merely two small subeircnlar de- 

 pressions near thi^ edge of the bone, not difiVring much from each other in size or shape. 

 They an' separated by a proujiuent process on tlH> edge of the l)oiie antcrioily on tho 

 median line. The end of the hone is, as usual, divided into three heads, separated by 

 narrow but very deep sulci. Of these heads the middle is the largest, and directly iii 

 the liiu' of the bone ; the outer is placed a little higher n\>, but nearly in the sanu' plane. 

 The inner, however, beside being much higher uj), is i>laced far around toward the pos- 

 terior aspect of the bone. The articular faces of these heads present in a high degree 

 of perfection the peculiar shape by which extension of the toes at the same time 

 abducts them, and vice vcrsd. 



