MUSCULAR ANATOMY ' 77 



on the penguin, we have only two recent memoirs which 

 contain anything Hke a complete account of the muscular 

 structure of a given type. These are the book upon Corvus 

 cdrax by Shxjpeldt and a paper by Chalmers Mitchell 

 and myself upon Palamedea. The most comprehensive 

 general account of bird muscles is unquestionably that of 

 Gadow in Bronn's ' Thierreich.' I shall base the following 

 account of avian musculature largely upon the last-men- 

 tioned work, adding to it only such details as were inacces- 

 sible to Gadow at the time of its publication. The muscles 

 known to vary will naturally be treated at greater length 

 than those of whose comparative structure but little is 

 registered. Gadow allows altogether 112 separate muscles 

 and sets of muscles like those of the ribs, arranged in a 

 serially homologous row. Some of these are, however, 

 divided again. Of these, so far as we know at present, the 

 following are of the greatest systematic importance, as present- 

 ing really considerable variations even to disappearance : — 

 V GlutcBus maximus, gl. anterior. 

 - Obturator internus. 



Femorocaudal and accessory femorocaudal. 



Ambiens. 



Semitendinosus and accessory semitendinosus. 



Biceps femor\s. 



Semimembranosus. 

 ^ Flexores profundi hallucis et digitorum. 



Peronei. 



Tibialis anticus. 



Pectoralis primus, p. secundus. 



Deltoid. 



Patagialis. 



Biceps. 



Anconaus. 



Expansor secundariorum. 



Cucullaris propatagialis. 



The value of muscles in classification has been highly rated by 

 many ornithologists, especially, of course, by Gabeod, Foebes, and 

 FtJEBEiNGEB. It is, however, only a comparatively small number 



