202 



NORTHERN ZOOLOGY. 



Tribes of 

 Insessores. 



CONIROSTRES 



Dentirostres 



FlSSIROSTRES 



Tenuirostres . 



scansores 



Analogies. 



Bill much compressed ; feet adapted both 

 for walking and perching; wings 

 lengthened. 



Bill stronger, notch more distant; wings 

 more rounded ; claws larger, very 

 acute. 



Bill depressed, bristled at the base. 



Bill very slender ; rictus smooth. 



Bill entire, or nearly so; hind toe 

 lengthened. 



Sub-families of 

 SylviaDjE. Typical Genera. 



SylviancB. 



Syl 



via. 



Philomelina;. Philomela. 



SaxlcoliruB. 

 MotacillincB. 



Parlance. 



Saxicola. 

 Motacilla. 



Parus. 



On duly investigating- this table, the ornithologist will detect many relations 

 of peculiar interest, which we cannot at present dwell upon. The two first, 

 indeed, are so faint, in comparison with the three last, that we do not feel per- 

 fectly sure whether — having now traversed over one half of the Dentirostral 

 circle, — the analogies of the typical groups are not reversed ; in other words, 

 whether the Pkilomelince do not represent the Conirostres through the medium of 

 the Merulinte ; and the Sylviance the Dentirostres through the medium of the 

 Myotherince ; but this will not in the least affect the progression of the affinities 

 as here exhibited. 



It will be sufficient, for our present purpose, to intimate the probable situation 

 of such species as are subsequently described. It is singular that in the sub- 

 family of 



SAXICOLIN^, 



only one form has hitherto been discovered in the whole extent of America ; this 

 is typically represented by the well-known " Blue bird" of Wilson, the Sialia 

 Wilsonii of our Mexican Synopsis. Another species, our Sialia Mexicana* , is 

 found on the table land of Mexico ; and a third, still more distinct, was first dis- 

 covered in these expeditions. The intimate connexion between this group and 

 our European Robin, must be so evident to all who have perused the pages of 

 Wilson, that we are justified in viewing it as a sub-genus, or the American type 

 of Erythaca, Sw. ; the Australian form is given in Petro'ica, Sw. ; the African 



* Sialia Mexicana, Sw. — Size of S. arctica ; upper plumage bright purple-blue, chin and throat the same ; across 

 the breast a rufous band, which colour is continued on the sides and flanks ; middle of the body, vent, and under tail 

 covers light-blue, inclining to white. Total length 6^, wings 4^, tarsi f, tail 3 inches. Inhabits Mexico. In Mr. 

 Taylor's collection. 



