1907.] TO THE OSTEOLOGY OF BIRDS. 371 



as in some forms, as in the Tyrannidse for example, and in Neto- 

 tonia among the Mnscicaj)id{B, it does not exceed the humerus in 

 length, while in others, as in the Gymnorhinse, it considerably 

 exceeds the hvuiierus, being as long as, or slightly longer than, 

 the forearm. Pityriasis, however, among the Gymnoi-hinse is 

 exceptional : all the segments of the wing being short, the fore- 

 arm especially so ; but this, it is to be noted, is associated with a 

 relatively shallow sternal keel. The intermetacarpal jDlate is 

 well-developed, and as a rule there is a deep groove along the 

 dorsal aspect of Mc. II. for the tendon of the extensor indicis 

 longius. This groove is exceptionally deep in Gymnorliina and 

 the Hirundinidfe. 



In the Swallows indeed the manus has become considerably 

 modified in response to the great strains put upon it. And this is 

 especially noticeable with regard to Ph. 1 of D. II. This phalanx 

 is of great breadth, flattened dorsally, and widest at its distal end : 

 while on its ventral aspect it presents the appeai-ance of an oblong 

 bone deeply hollowed along its centre, and having its preaxial 

 border produced proximad in the form of a tubercle to afibrd extra 

 ligamentary attachment to its metacarpal. Metacai-pal III. is 

 produced for a considerable distance beyond Mc. II. and supports 

 a slender phalanx. The terminal phalanx of D. II. (Ph. 2) is 

 very small. In the Hirundinidse the humerus does not exceed 

 the carpo-metacarpus in length. The pollex is greatly reduced. 



Compared with the Eurylsemida? the wing, in the forms herein 

 described, shows a more specialised condition in the greater devel- 

 opment of the deltoid ci-est and ectepicondylar process of the 

 humerus ; and in the broadening of the metacarpals I. & II. 



viii. The Pelvic Limb. 



When the skeletons of a sufficiently large number of genera 

 and species have been got together, it will probably be found that 

 the pelvic limb will reveal useful characters for systematic pur- 

 poses. With the limited material at my disposal however, I can 

 do no more than outline the general characters of this portion of 

 the skeleton. 



The femur, which is relatively long and slender, appears to be 

 pneumatic only in Tylas, Newtonia, Euryceros, Artamia, and 

 Artamus. The popliteal fossa is obsolete. The tibial condyle 

 develops a more or less prominent spur laterad of the slight de- 

 pression which marks the popliteal depression in Newtonia, Vireo- 

 lanius, and Paradisea. As a rule the tibial and fibular condyles 

 are subequal, but in the Gymnorhinse and the Dicruridse the tibial 

 condyle is markedly larger. 



The tibio-tarsus is long and slender, and slightly inflected at 

 the tip : the intercondylar gorge is deep and wide ; while the 

 extensor groove immediately above is traversed by a bony " ex- 

 tensor bridge," which is generally wide. Immediately above the 

 bridge, on the fibular side of the shaft, is a more or less prominent 



