1907.] TO THE OSTEOLOGY OF BIRDS. 367 



DiCEURiD^. I Gymnorhinje. 



Edoli'us. ' Fityriasis. 



Thoracic 1 1 



Lumba,!" 3 3 



Lumbo-sacral 1 i 2 



Saci'al 2 2 



Caudal 4 + 6 5 + 6 



11 



Total 17. 



13 



Total 1 9. 



Compared with the Tracheophone Passeres these numbers are 

 of some interest, inasmuch as they show that the vertebral column 

 of the forms now in question has become more specialised by the 

 reduction in the number of the synsacral and free caudal vertebr?e. 

 In the Tracheophonse the number of these vertebrae is never less 

 than 19, the lumbo-sacrals are never less than two — generally three 

 ai-e present : as against the single vertebra of many Tyrannidse, 

 Muscicapidse, aiid Dicruridse. 



iv. The Ribs. 



The number of the ribs has already been referred to, but a 

 brief reference may be made here to one or two structural pecu- 

 liarities of interest. In Pit't/7'iasts, for example, the upper portions 

 of the thoracic segments are conspicuous for their great breadth, 

 as well as for the unusually large size and breadth of the un- 

 cinates which ai'e attached to their respective ribs by broad 

 oblong bases. Bitchanga, one of the Dicruridse, shows an apjoroach 

 to this condition. Only in Gymnorhina, apparently, has the 

 last thoracic rib retained its uncinate. It would be interesting to 

 discover whether there is anything in the mode of life of the 

 Gymnorhinse which could account for the width of the thoracic 

 ribs and uncinates just referred to. 



V. The Sternum and Shouldee-Girdle. 



With the exception of the Pittida^ the sternum is of the typical 

 Passerine type in all the forms herein described, having but a 

 pair of posterior notches and a long Y-shaped spina externa. The 

 peculiar sternum of Pitta has already been described by me (5). 

 Except that the corpus sterni varies in its relative length, the 

 sterna now under consideration afford no appreciable distinguish- 

 ing characters. Only the Gymnorhinfe and the Paradiseidse have 

 the sternal plate elongated, and even here this is not a very striking 

 feature. 



The coracoid grooves in all cases are deep ; and similarly, in 

 all cases, the articular surfaces for the sternal ribs are confined to 

 the anterior lateral processes. 



The carina sterni is deep in all save the Gymnorhinse, though 



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