MEMOIRS 



READ BEFORE THE BOSTON SOCIETY OF NATURAL HISTORY. 



VOLUME I. PART II. 



I. The Osteology of the Colynibus torquatus ; with Notes on its Myology. 

 By Elliott Codes, A. M., M. D. 



Read September 16th, 1863. 



JL HE Natatores Brachypteri, or JJrinatores, so restricted as to exclude the Penguins, (Plihpteri,) 

 form an exceedingly natural group, quite closely adhering to a peculiar type of structure, 

 as regards their bony framework and the muscles which act upon it. Their essential char- 

 acteristics are found in the possession of a structure which, while it secures quite vigorous 

 powers of flight, yet attains to by far its most perfect development in the production of 

 natatorial powers, (unequalled except by those of the Penguins,) at a great sacrifice of capa- 

 bilities for terrestrial locomotion. Progression on land is generally slow, awkward, and con- 

 strained; and is seldom or never protracted to any considerable distance, the bird always 

 remaining in close proximity to the water. On the other hand, progression on or through 

 the water is accomplished with a degree of facility and energy which at once stamps a 

 peculiar character upon the whole tribe. 



These remarks apply with particular force to that family of birds of which the common 

 Loon may be considered as typical. In the genus Colymbus, the peculiarities of structure 

 above alluded to reach their maximum of development, for the production of unsurpassed 

 natatorial powers, at the expense of capabilities for terrestrial locomotion, which latter 

 are remarkably imperfect. Both the osseous and the muscular system, therefore, of Co- 

 lymbus torquatus, are probably typical of the morphology of these systems throughout the 

 Urinatores, and are thus specially interesting and instructive as exemplifying the natatorial 

 type of structure in a very perfect manner. The descriptive anatomy of them is applicable 

 in a greater or less degree to the other genera of the tribe. The Podicipidcc are of course 

 the most intimately allied ; some of the genera of the Alcidce may be more aberrant. 



Although peculiarities are found in the whole structure of the bird, yet they of course 

 are most marked in the posterior extremities ; and I have therefore, in my descriptions, 

 entered specially into detail regarding these parts, passing over other portions in a more 

 summary manner. In the following pages, so far as the bones are concerned, it has been 

 attempted to present the descriptive anatomy of the entire skeleton ; while in the account 

 of the muscles, only the more important have been noticed, special attention having 

 been paid to those of the posterior extremities. In a paper like the present, it seemed 



MEMOIKS BUST. SOC. NAT. HIST. VOL. I. Ft. 2. 31 APEIL, 1866. 



