STUDIES OE THE MACROOHIEES. 



363 



erhaps rudimentary, vertebra at the end of the series of the 

 audal segments. 



Further, I find the arrangement of the free vertebral ribs and 

 'heir uncinate processes the same for all Hirundinidae, as I found 

 them to exist in the Violet-green Swallow in my former memoir, 

 ^•^his arrangement consists in their having 12 cervical vertebrae 

 .I'i^t do not possess free ribs ; the thirteenth has a rudimentary 

 pair ; the fourteenth has them better developed, and even may 

 have uncinate processes upon them ; the fifteenth are the first to 

 connect by costal ribs with the sternum, as do the ribs from the 

 sixteenth to the nineteenth vertebrae inclusive. The twentieth 

 is the first vertebra appropriated by the pelvis, and this latter 

 compound bone monopolizes ten of these segments, so that the 

 first free caudal is the thirtieth vertebra of the spinal column. 



Thus far at least one Swift {Micropus) was found by me to 

 exhibit an arrangement similar to this, and later on we may look 

 into the matter for CJicetura. 



The Humming-birds possess, as I have elsewhere stated, but 

 32 vertebrae and a pygostyle in their spinal column. 



Every species of our Swallows possesses a pelvis of a pattern 

 characteristically its own, so that had we before us a dozen pelves 

 of Progne, a dozen of Ghelidon, and a dozen of each of the others 

 we should have no diflBculty, after once becoming acquainted 

 with them, in picking out the several varieties correctly. Then, 

 again, these pelves all strictly fall within the general description 

 applied to what we please to call a Passerine pelvis, so far as our 

 present knowledge and ideas of such a bone can be formulated. 

 Now there is nothing that I can at this moment place my finger 

 upon in the pelvis of a Swift that debars it from being classed in 

 the same category ; and indeed, when we come to examine into 

 the matter closely, the differences between the pelves of Micropus 

 and Progne are no greater than are the differences between the 

 pelves of Progne and Ghelidon. 



Ornithologists have long ago placed on record descriptions of 

 the shoulder-girdle and sternum of Hirundine birds, and the 

 morphology of tliese parts in them is so well-known that to say, 

 that although each species of Swallow has a characteristic form of 

 sternum and shoulder-girdle of its own, these elements of the 

 skeleton in all of them are strictly Passerine, — will sufficiently 

 meet our aims in the present connection. 



In my memoir in the P. Z. S. already referred to I made com- 



LINN. JOUBN. — ZOOLOGY, YOL. XX. 28 



