STRUTHIONES .-,11 



different. The last few tracheal rings are incomplete 

 posteriorly ; the space left between them is continuous with 

 a membrana tympaniformis. There is no pessulus or 

 intrinsic musculature ; in the division of the last tracheal 

 rings there is a suggestion, faint perhaps, of the tracheal 

 syrinx. Dromceus, as might be imagined, closely resembles 

 Casuarius. It has, however, a peculiarity which has been 

 fully gone into by MuETE, 1 who quotes the pre-existing 

 literature upon the matter. In front of the trachea some 

 way down the neck a certain number of the tracheal rings 

 are deficient in front ; and the lining membrane of the tube 

 here projects as a sac, which can be inflated, and has, no 

 doubt, something to do with the drumming voice of the 

 bird. The accompanying illustration shows this peculiarity, 

 which is not met with in the cassowary. 2 



As to osteology? in RJtea (fig. 77, p. 140) the vomer tends 

 to be bifurcate posteriorly where it is much widened out, and 

 articulates both with the palatines and the pterygoids. The 

 palatines are posteriorly flat and fenestrated. The maxillo- 

 palatines are thin plates which meet the anterior bifurcation 

 of the vomer. The descending process of each lacrymal 

 has a large foramen, the presence of which led B. 0. CUNNING- 

 HAM to distinguish Eh. Darwini from Eh. americana, where 

 the foramen is simply a notch. GADOW, however, showed 

 that the question of notch or foramen is simply individual 

 variability, and I am in a position to assert the same of Eh. 

 macrorhyncha. The existence of a complete descending 

 process of the nasal has been denied. PAEKEB, however, 

 has figured an ascending pillar of bone from the maxillary, 

 and in a specimen of Rh. macrorhyncha this was joined by a 

 suture to the anterior margin of the lacrymal. It has, it is 

 true, no connection with the premaxillary part of the nasal ; 

 but this can scarcely interfere with a comparison of the 



1 ' On the Tracheal Pouch of the Emu,' P. 7. S. 1.867, p. 40o. 



- For the lungs and air sacs of Struthiones see ante, p. 495. Those of 

 Rhea have been described by W. N. PARKER, ' Note on the Respiratory Organs 

 of Rhea,' P. 7. S. 1883, p. 141 ; of Dromceus by MALM, 'Om Luftrur-s-ickrn,' 

 &c., Off. K. TV/. Ak. Forh. 1880, p. 33. 



3 PANDER and D'ALTON, Die Skclcte rfcr Ktraussartic;cn VUgcL Bonn, 1827. 



