28 STRUCTURE OF GALLINACEOUS BIRDS. [CH. I 



notched sternum, the more rudimentary vomer, and the 

 abnormal position of the hallux in the Alectoropodes. 

 This is very likely so, but as Fiirbringer 1 has pointed out, 

 the structure of the soft parts of the Megapodes are more 

 different from what is found in the Curassows. The latter 

 often have a convoluted windpipe, which does not occur 

 in the Megapodes, but is met with in some Guinea fowls 

 and in the Grouse (Tetrao urogallus). The Megapodes 

 have lost one of the two carotid arteries, and their oil 

 gland has not the tuft of feathers found in other Galli- 

 naceous birds ; in fact, as regards internal structure other 

 than that of the skeleton, the Cracidse are not so very 

 near to the Megapodes. All these structural features 

 will seem perhaps of small moment to the student of 

 invertebrate anatomy ; but it must be remembered that 

 birds form a very circumscribed group ; the anatomist 

 is glad of the smallest characters upon which to found 

 differences ; and the differences enumerated are not small, 

 considering the characteristics of the order. Apart, how- 

 ever, from these differences it does appear the two families 

 Cracidse and Megapodida? are the most primitive Gallin- 

 aceous birds now in existence ; not only do the two 

 points referred to above tend to show this, but we might 

 also perhaps urge the " reptile- like habit " which the 

 Megapodes have of laying their eggs in a heap of dead 

 leaves and abandoning them to the kindness of nature 

 a habit which of course recalls that of nearly all Reptilia. 

 Moreover neither the Curassows nor the Mound-builders 

 show to anything like so great a degree that difference in 

 1 Untersuchungen zur Morphologie der Vopel. 



