366 PEOFESSOE OWEN ON THE GENUS DINOENIS. 



3 inches from the proximal end, is a rough low ridge and surface (ib. fig. 1, o), 

 answering to the stronger prominence in the Cnemiomis (marked y in fig. 1, pi. 66. 

 Zool. Trans, vol. v.). 



The extensor canal (PI. LIX. fig. 1, p), its bridge (q), and lower outlet (r) repeat or 

 retain the dinornithic characters'. The tuberosity from the outer pier of the bridge 

 is strongly developed. A flat, rough surface, 3^ inches in extent, pointed above and 

 broadening to 10 lines below, marks the inner side of the distal end of the shaft. On 

 the other side of that part is a rough, narrow surface, suggesting a third attachment of 

 the pointed end of a long and slender fibula. The configuration of the distal trochlear 

 articulation closely adheres to the dinornithic pattern. The shallow pit receiving the 

 ectocondylar convexity (PI. LIX.) is well defined. 



The epicnemial process is developed as an epiphysis ; it retains this character in the 

 tibia, 14 inches in length, of a young Emu {Dromaius novcB-hollandice), and includes the 

 commencement of the procnemial and ectocnemial ridges ; it might pass for a distinct 

 bone (the patella), as the distal ejsiphysis (ib. fig. 4, a, v) has been conjectured to 

 represent an astragalus ; but the cartilaginous homologue of the patella in Dromaius, 

 which plays upon the rotular groove of the femur, is ossified in some birds, notably in 

 the Penguins and Loons [Colymhus), in which the development of the epicnemial process 

 is in excess^, and with which the true patella coexists. 



The distal epiphysis (PI. LIX. fig. 4) has eff'ected a closer union with the shaft of 

 this tibia, agreeably with the law of its relation to the course or direction of the 

 medullary artery; the portion of the shaft developed epiphysially (ib. a) with the 

 trochlear articulations [b) ascends nearly three inches up the fore part of the diaphysis, 

 and develops the groove and process for the ligamentous bridge of the " tibialis anticus " 

 tendon. 



Femur. — In no specimen that has hitherto reached me are the dinornithic modifica- 

 tions of the femur more definitely and strongly marked than in the present example 

 (Pis. LX. & LXL), in which the eff'ects of the usual posthumous abrasion are limited to 

 the articular prominence of the head, and to parts of the margin of the trochanter and 

 hinder projections of the outer condyle. I propose, therefore, to take the opportunity 

 of noting the characters more in detail than has been done in previously figured, less 

 complete, and commonly larger specimens. 



The head {a) of the femur, in all the species of Dinornis, is less sessile than in birds 

 generally ; but the part supporting it has more the character of a neck in the present 

 species than in Binorms giganteus^, in JXnornis casuarinus*, or in Dinornis maximus^. 

 The constriction aflfects the entire cuxumference, but is deepest, as usual, anteriorly, 



' These are shown, in contrast with those in the tibia of Oastomis parisiensis, in the ' Quarterly Journal of 

 the Geological Society,' 1856, pi. iii. figs. 1 & 2, p. 204. 

 ' Owen, ' Anatomy of Vertebrates,' vol. ii. p. 83. fig, 34, 1. 

 » Trans. Zool. Soc. vol. iii. pi. 44. fig. 1. * lb. pi, 46, figs. 1, 2, ' Ib. vol. vi. pi. 89. fig. 1. 



