1877.] 



ANATOMY OF PASSERINE BIRDS. 



451 



almost every order — in Rhea and the Megapodes among the Galli- 

 formes, in Arctica alle and Turnix among the Charadriiforraes, in 

 Sulafusca and Plotus anhinga among the Ciconiiformes, &e. The 

 disappearance here and there of the ambiens muscle and of the femoro- 

 caudal, as well as of the colic cajca, all come under the same category, 

 as simple operations which lose their significance in the determi- 

 nation of affinity in proportion to the frequency of their appearance, 

 or to the facility with which they are induced, as I would assume. 



The figure of the superior surface of the skull of Furnarius rufus 

 (p. 450), when compared with those of Charadriiform birds in 

 my paper above quoted', will show the resemblance between the two, 

 as far as the point under discussion is concerned. 



In questions of doubtful affinity among the birds under considera- 

 tion, this character proves to be of service. For example, the genus 

 Margaronis is differently placed by leading ornithologists — by some 

 along with the Sclerurinae on account of the shortness of its outer 

 toe, by others with the Dendrocolaptinae because of the stiffness of 

 its tail-feathers. From the skull, an example of which I have had 

 the opportunity of removing from a skin of Megarornis perlata, 

 through the kindness of Mr. Salvin, I feel no doubt that it is not 

 Dendrocolaptine, because the nasal bones agree exactly with those of 

 Furnarius rufus and the other schizorhinal Passeres above mentioned. 



I may also mention that in these schizorhinal tracheophone 

 Passeres, as also in their allies the Pteroptochidae, the maxillo-pala- 



Fig. 4. 



Palatal view of skull of Pfcroptochus alhicollis. 



tine plates of the maxillary bones, instead of terminating by blunt 

 uncurved tips, as in the non-oscine (mesorayodian^) Passeres generally, 

 including Dendrocolaptes, Thamnophilus, and their nearest allies, 

 are slender and curved backwards as in the Oscines. A study of 

 the superb plates in Mr. Parker's Memoir on ^^githognathous 

 Birds ^ will illustrate this point, which an inspection of other skulls 



' P. Z. S. 1873, p. 34. ' P. Z. S. 1876. 



^ Trans. Zool. See. vol. ix. p. 289, pi. Ivi. figs. 8-10. Ivii. figs. 8-10, et lix. 

 figs. 1-3 & 6-8. 



29* 



