436 PROFESSOR OWEN ON MACEOPUS. 



prominence (/() to that which, bending forward, at /*', terminates the long ischio-pubic 

 symphysis [k G4»» 63**). The hinder end of this symphysis is formed by a triangular 

 epiphysis, which coalesces ultimately with both ischia. Each ischium rajjidly expands 

 as it advances forward, or " hsemad," to form the hinder half of the ischio-pubic sym- 

 physis and of the foramen ovale (o). The outer surface of this expansion is traversed by 

 an oblique rough ridge (63"); the inner surface is smooth. The concave border between 

 I and h (PI. LXXX. fig. 2) represents the " lesser ischiadic notch " of anthropotomy. 

 The position of the union and ultimate coalescence of the symphysial branch of the 

 ischium (63««) with that of the pubis (64*») is indicated, in the adult, by a low angle 

 (fig. 1, v) projecting into the " foramen ovale " (o). 



The pubis (64) contributes one half to the ilio-pubic process (e) by a projection 

 answering to the pectineal process of the pubis in Monotremes and many Reptiles; 

 and the lower and outer part of that expanded end of the bone forms the pubo-cotylar 

 tuberosity (g4») and a small contiguous part of the acetabulum. Contracting- to a 

 narrow plate of bone, the pubis inclines downward and forward, slightly expanding, to 

 join its fellow at the fore half (64*») of the ischio-pubic symphysis, where it extends 

 backward and contributes to the same proportion, and to the anterior part of the 

 circumference, of the " foramen ovale " (o). 



The acetabulum (PI. LXXIX. t, t'; PL LXXX. fig. 2, x) has a subtriangular brim, the 

 angles rounded off' and swollen to form the ilio-cotylar (^'), the pubo-cotylar ( 64* ), and 

 the ischio-cotylar ( 63* ) tuberosities. The margin subsides between the two last-named 

 prominences, and becomes thinner between the two first. The cotylar pit {x) and notch 

 [y) are deep. 



In the development of the Macropodal pelvis (PL LXXIX. fig. 3) three epiphyses, or 

 distinct centres of ossification, are superadded ; but they have as little segmental or 

 general homological signification as the basisphenoid epiphyses in the cranium of the 

 Bird. One of these epiphyses (ib. 64') belongs to the acetabular end of the pubis, and 

 becomes the pubo-cotylar tuberosity (ib. fig. 1, 64*); a second belongs to the symphy- 

 sial ends of the pubis, and forms the haemal projection at the fore part of the ischio- 

 pubic symphysis ; a third epiphysis (ib. fig. 3, /*') belongs to the symphysial ends of 

 the ischia, and forms the haemal prominence at that end of the symphysis. 



The epiphysis {k) gives attachment to the entobasilar articular ends (ib. fig. 1, r, r) 

 of its marsupial bones. Each of these bones is 2 inches 7 lines in length, 6 lines in 

 breadth at the ectobasilar process (s), decreasing in breadth from that part to both the 

 attached (t) and the free (t) extremities : the former is slightly thickened and expanded 

 where it is bound by ligaments to the pubic epiphysis (k). An oblique low ridge runs 

 along the outer surface of the pelvic end of the bone ; the rest is a thin plate with a 

 sharp edge at the outer or lateral border. 



In the figure of " the pelvis of a female Kangaroo," most probably of M. major, 

 apparently of the natural size, given by Home (Lectui-es on Comparative Anatomy, 



