248 PEOFESSOR OWEN ON THE GENUS DINOENIS. 



or double-ridged character of the centrum (as shown in figs. 4, 5 and 6) is indicative 

 of the attachment of depressor muscles. 



The caudal vertebrae in natural articulation curve slightly downward at the terminal 

 third of the series. The length of this series following such curve is 5 inches 3 lines. 



In the skeleton of Binornis elejjhmitopus^, described and figured in Trans. Zool. 

 Soc. vol. iv., nine caudal vertebrae were definable, most of them more or less muti- 

 lated, but the last one sufficiently preserved to show the absence of the characteristic 

 modifications of that part of the tail-skeleton in most birds of flight^. The caudal 

 vertebra of Binornis maxivuts, described in the Memoir (part xxii. fig. 36) as the second 

 of the series, corresponds in the main with the second in D. parvus ; but the divisions 

 of the neural spine, or divergent processes from the roof of the neural arch, are rela- 

 tively longer than in B. maxiinus, and the interspace is consequently deeper and wider. 

 In the three coalesced terminal caudals of, probably, Binornis crassus, described p. 180, 

 loc. cit., and figured (figs. 38, 39), the better-marked indications of the line of confluence 

 of the penultimate and last vertebra bear put the interpretation of the corresponding 

 feebler ones in B. parvus ; but the parapophysis of the last vertebra in B. crassus is 

 not developed in the smaller species. The foramen indicative of the exit of the hind- 

 most nerve is relatively longer in B. crassus, and is repeated on both sides. The 

 antepenultimate caudal in I), crassus is relatively shorter than in D. parvus. Of the 

 three sides of the terminal coalesced caudals in B. parvus, the lower one is the 

 narrowest, not the broadest as in B. crassus. The penultimate centrum of B. parvus 

 has not the excavation of the lower surface which is described and figured in that 

 centrum of B. crassus. But all the essential modifications of this part of the skeleton 

 in the present extinct wingless genus of birds are repeated in Binornis parvus, and are 

 manifested with slight modifications in the caudal vertebrae of Apteri/x^. 



§ 8. Femur. 

 Notwithstanding the extreme difference of size, the femur oi Binornis parvus (PI. LVI. 

 figs. 1-6) presents the generic characters of the bone as well marked as in Binornis 

 maximus*, and as clearly differentiated from those of the femur of Apteryx australis. 

 The only trace of a transition is in the slight degree of relative slenderness of the shaft 

 to the length of the bone as compared with that in the taller species of Moa ; but all 

 the characters connected with muscular power or work are as strongly marked in 

 B. parvus as in any of the larger forms of the genus. The thickness of the wall of 



' Memoirs, &c., 4th, 1878, p. 223, pi. Ix. Ibid. p. 233. 



' In Chauna chavaria the caudals precede the coalesced group of four, the foremost of which barely surpasses 

 in height the preceding free caudals. (See the excellent and exhaustive work by Eyton, ' Osteologia Avium,' 

 pi. 2.5 a. tig. 3). 



• Trans. Zool. Soc. vol. ii. p. 288. 



* Trans. Zool. Soo. vol. vi, 1868, p. 498, pi. Ixiiix. 



