A.A2 Corrrs/>Of/tfr)/ce. [Octoht-r 



typical plan for the vast inajoiitv of average Passeres. A difference is met 

 .with though in the tail vertebrie, for in the specimens at mv hand Habia 

 possesses seven free caudals and the pygostvle, while Pipilo has but six 

 and the terminal piece. In Piranga, too, we find but six caudal vertebra, 

 and the pygostvle, while this also seems to be the number in fcteria, and 

 in a former memoir I recorded the same in Molo/knis nter. 



With barely an apology of a structural difference between them upon 

 which to base a substantial distinction, the pelvis in Habia sees almost 

 its exact counterpart in the corresponding bone in the skeleton of Pipilo 

 m. megaloiivx- Both are typically passerine, and so well known is the 

 passerine pelvis in such genera as these, that to enter upon its description 

 is by no means necessary. Pifilochlorurns has a pelvis which differs from 

 the pelvis in P. m. iiiegalonyx, as well as from the pelvis in Zo7iotric/iia 

 coronata, in that in it is the fourth sacral vertebra, counting from the 

 last forward, that extends its diapophjsial braces opposite the acetabula, 

 instead of the third as in the excepted species, and a difference of arrange- 

 ment also exists in that an additional yertebra, anteriorly, extends its 

 lateral processes to meet the ilium upon either side, there being three 

 each in P. m. megalonyx and Zonotric/tia, and four in P. chlorurus. I 

 should like to examine more material before pronouncing upon the sig- 

 nificance of this departure, and more especially skeletons of Ember>iagrci 

 rufivirgata. Piranga ludoviciana and Icteria have pelves almost iden- 

 tically alike, it being in each case the fifth from the last sacral vertebra 

 that throws out the long strut-like apophysial arms to act as braces oppo- 

 site the acetabula. Calamosfiza possesses the same arrangement of the 

 vertebrae in its pelvis, but here the bone is apparently not as wide for its 

 length as it is in Habia, though no satisfactory differences exist between 

 several of these pelves, upon which to base strong family, or even generic 

 lines. 



Few differences again are to be found in the sternum of the species we 

 have under consideration ; the common pattern of the bone as seen among 

 the smaller average passerine birds of this country is well shown in my 

 figures of it in Otocoris (Osteology of ^. alfestris, figs. 22, 24, 27, and 38) ; 

 in Habia the anterior carinal angle is pointed and the keel itself is but of 

 moderate depth, while among the Pipilos, and in Zottotrichia, the anterior 

 carinal angle is rounded, and the keel much shallower, markedly so in the 

 ground-loving species of the first-named genus. I am strongly inclined, 

 however, to attribute this last character to physiological adaptation rather 

 than to an evidence of affinity. These Towhees spend much of their time 

 hopping about beneath the shrubbery of their places of resort, and by no 

 means use their wings in flight so often as other fringilline species, and 

 consequently develop less their pectoi-al muscles, which are attached, in 

 part, as we know, to the sternal carina. True Tanagers, as I have else- 

 where pointed out, have an osseous bridge extending across thie top of the 

 manubrium to the anterior margin of the body of the sternum, and if it l)e 

 constant, it is an excellent character for this family. It is absent in such 

 a genus as Icteria, and in all the Fringillidie now at my hand. 



