144 



symphysis. How easy to suggest that this single symmetrical bone 

 may be the representative of the os pe/iis removed from the glans to 

 the root of the iutromittent organ ! It is obviously a mere epiphysis 

 of the ischium. 1'he circumference of the acetabulum is always in- 

 terrupted by a deep notch opposite the obturator-foramen, which is 

 traversed by a ligamentous bridge, and gives passage to the vessels 

 of the Harderian gland lodged in the wide and deep acetabular fossa. 



" The femur is a straight or nearly straight long cylindrical bone, 

 having a hemispherical head supported on a very short neck, espe- 

 cially in the Petaurists, and situated here almost in the axis of the 

 shaft, above and between the two trochanters, which are nearly of 

 equal size. In the Kangaroos and Potoroos the head of the thigh 

 bone is turned more inwards, and the outer or great trochanter rises 

 above it. In other Marsupiata the great trochanter is less developed. 

 In all a strong ridge is continued downwaids to a short distance' 

 from the trochanter ; and this ridge is so produced at the lower part 

 in the Wombat as almost to merit the name of a third trochanter. 



" In the Wombat and Koala there is no depression for a ligamentvm 

 teres which nevertheless exists in the latter. 



" The shaft of the bone presents no linecK aspcrce. The canal for 

 the nutrient artery commences at the upper third and posterior part 

 of the bone in the Koala, and extends downwards, contrary wise to that 

 in man and most other Mammalia. At the distal extremitj' of the 

 femur the external condyle is the largest, the internal rather the 

 longest. The intermediate anterior groove for the patella is well 

 marked in the Perameles where the patella is fully developed, but is 

 broad and very shallow in the Phalangers and Dasyui'es, where the 

 tendon of the rectus is merely thickened, or offers only a few irregular 

 specks of ossification ; and the corresponding surface in the Petau- 

 rists, Wombat and Koala, is almost plane from side to side. 1 find 

 distinct but small bonj- patella; in the Macropus Bennettti. 



"The tibia presents the usual disposition of the articular surface 

 for the condyles of the femur; but in some genera, as the Wombat 

 and Koala, the outer articular surface is continuous with that for 

 the head of the fibula. In the Kangaroos and Potoroos the 

 anterior part of the head of the tibia is much produced ; and 

 in the young animal its ossification commences by a centre dis- 

 tinct from the ordinary proximal ejjiphysis of the bone. A strong- 

 ridge is continued down from this protuberance for about one 

 sixth the length of the tibia. In the Koala a strong tuberosity 

 projects from the anterior part of the tibia at the junction of the 

 upper with the middle third. In this species, and in the Wombat, 

 as also in the Opossums, Dasyures, Phalangers, and Petaurists, the 

 shaft of the tibia is somewhat compressed and twisted ,• but in tlie 

 Kangaroos, Potoroos, and Perameles, the tibia is prismatic above 

 and subcylindrical below. The internal malleolus is very slightly 

 produced, perhaps most so in the Wombat. 



" The fibula is complete, and forms the external malleolus in all the 

 Marsupiata. In one species of Hypsiprymnus, and in one sjjccies of 

 Perameles, it is firmly united to the lower part of the tibia, though the 



