Art. XIV.— Osteolog-y of lianius liidoTicianiis exciibi- 



torides. 



By R. ^W, Sliufcldt, III. D., First £.ieut. Med. Dcpt. U. S. Army. 



Mr. Eobert Eiclgway, in his carefully prepared check-list of IS'orth 

 American Birds (Bull. !N"o. 21, JSTomenclature of ^N". American Birds, 

 chiefly contained in the U. S. i^at. Mus., Washington, D. C), gives us 

 the representatives of Laniidce, the species horealis and ludovicianus, 

 with the two occidental varieties of the last, robustus and excuhitorides, 

 which latter form we have chosen as the subject of this paper to demon- 

 strate the peculiarities of the skeleton of these interesting birds. The 

 habits of the Shrikes are well known to all ornithologists, so one will not 

 be surprised, after a view of Fig. 100, in the plate (where our subject has 

 been made, by the aid of the dissecting knife and maceration, to exhibit 

 one of the truest indices of his character), to find the large, semi-hawk- 

 like skull surmounting the remainder of a bony frame-work, that might 

 easily be mistaken as belonging to a Thrush or any other Oscine; but 

 it is this very characteristic that individualizes these truly passerine- 

 rai)torial birds. 



In the skull, divested of the lower jaw and hyoid arch in the adult, 

 we find that anchylosis of theprimoidal segments has been very thorough; 

 outside of the bony parts of the sense capsules — the tympanic elements 

 and the pterygoids are the sole escapers of this notorious feature in 

 avian craniology — indeed, we discover in the skull of this species, before 

 it has left the nest, that the primitive segments of the occipital vertebra 

 are well advanced towards permanent union, especially about the condyle, 

 traces of its formation being extremely difficult of discernment, and in 

 the mature bird this hemispherical facet for the atlas is exceedingly 

 diminutive, measuring only .5 of a millimeter in diameter. About the 

 basi-cranii we find the usual foramina for the exit and entrance of vessels 

 and nerves, and note in our examination that the anterior apertures of 

 the Eustachian tubes are double, very small, and protected by an osse- 

 ous lip from the basi-sphenoid. The foramen magnum is sub-circular 

 and of medium size ; together with the basi-cranii, it makes an angle 

 with the horizontal plane of 25°, the anterior bearing point being the 

 tip of the beak, and the two posterior bearing points being the internal 

 facettes upon the tympanies. That part of the cranium above, formed 

 by the frontals and parietals is very broad and smooth, and quite often 



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