460 Proceedings of Philosophical Societies. [June, 



detailed account of the important researches, by means of which 

 the Cheveriier Geofl'roy Sahit Hilaire has endeavoured to form a 

 comparison between the bony parts of the branchial apparatus 

 in fish, and those which perfonn analogous functions in the 

 skeleton of the three other classes of animals with vertebra. 

 This learned naturalist has this year presented to the Academy 

 several new memoirs on the same subject, and he has published 

 the whole in one volume, under the title of " Anatomical Philo- 

 sophy, or on the Respiratory Organs, considered with Respect to 

 the Determination and the Identity of their bony Parts," with 

 lOraezzotinto plates. 



The work of M. Geoffroy may be considered in three different 

 points of view ; it embraces, 



1. The enumeration and description of all the bones com- 

 posing each of the organs which contribute to respiration in fish, 

 and of those of some of the other classes, whenever it was 

 necessary to the plan of the author to describe them anew. 



2. The resemblances admitted by the author between the 

 bones, which had hitherto been supposed to belong exclusively 

 to fish, and those which he considers as analogous to them in 

 other animals with vertebree. 



3. The conclusions which he is led to form from these newly 

 discovered resemblances, as far as regards the nature and the 

 destination of the organs to which these parts belong. 



M. Geoffroy has thus carefully enumerated and described all 

 the minute parts which enter into the large branchial apparatus ; 

 those which form the honey arches on which the gills are sus- 

 pended ; those which support those arches ; those annexed to 

 them called the pharyngial bones ; those which cover them, and 

 bear the name of operculum, &c. He informs us of how many 

 bones the sternum is composed in the different classes of 

 animals with vertebrae, and how these parts are arranged in 

 them. He also gives new and curious details respecting the 

 composition of the different os hyoides, and respecting the points 

 of ossification, which are to be met with in the cartilages of the 

 different iarynges, and likewise on the resemblance between the 

 upper larynx of birds and that of the mammalia. 



This part of his work, which consists of positive facts, most of 

 them new, and all clearly described, will always remain a valuable 

 acquisition to science. 



The second part, which establishes the analogy of the bones 

 of which we have just spoken with those of the superior classes, 

 presents much greater difficulties, as may have been seen in our 

 last analysis. 



According to M. Geoffroy, the bones which form the gill 

 covers correspond with the frame of the tympanum and the small 

 bones of the ear, the bones .which bear the branchiostegal mem- 

 brane, proceed from an intermixture or intercalation of the pieces 

 of the sternum, between those of the on hyoides ; from a change of 



