2 THE MYOLOGY OF THE RAVEN. 



our dissection will be to demoDstrate and expose the 

 cutaneous system of muscles, or the dermal inuscles. 



The dermal muscles are principally of two kinds : 

 viz. the dermo-osseoiis, and the true de7'mals. The first- 

 named have their origin on some part of the skeleton, 

 and their insertion in the integuments ; while the second 

 kind both arise and are inserted in the skin or some 

 of its appendages. 



We never find all the known dermal muscles in any 

 one form ; they vary with certain characteristics of the 

 bird. The Peacock has a special dermal muscle to act 

 upon the gorgeous fan which it spreads, and is com- 

 posed of the feathers of the lower part of the back. 



Other birds having large crests, and peculiar skin 

 developments about the head, which require special 

 movements, possess the appropriate dermal muscles to 

 operate upon them. Again, all birds possess an enormous 

 system of minute muscles divided up into an infinite 

 number of fasciculi, to harmoniously act upon the 

 feather-quills, and collectively agitate the plumage. 

 These are quite conspicuous in the Raven, but will not 

 be especially dwelt upon. With an ordinary lens their 

 action may be studied with comparative ease in one of 

 the large quill-butts of the pinion, or tail. 



In the Raven the apteria are entirely devoid of 

 muscles, and even the other dermal muscles often 

 appear to turn out of their usual direction to avoid 

 these tracts. 



The muscles may be arranged, according to the usual 

 divisions of the body, into those of the cutaneous 

 system ; those of the head and neck ; those of the 

 trunk ; those of the upper extremity ; those of the 

 lower extremity ; and those devoted to the organs of 

 special sense. 



