134 



Bulletin American Museum of Natural History. [Vol. XXVII, 



question, by assuming the homoloo-y of the "columella-articular" with the 

 "malleo-meckehan." For if on the other hand the malleus be assumed to 

 represent the articular (a view which is supported by many authors) then 



Qu = I 



hfcv 



man Mai 



Fig. 5. Broom's theory of the evohition of the mammalian ossicula audit us. After Broom 

 (lettering m'odified). 



A. Embryo crocodile; B, hypothetical restoration of the conditions in an embr.vo C.vno- 

 dont ; C, embryo mammal. 



sup. St., suprastapedial. 



ex. col., extracolumella (= Malleus). 



St., stapes. 



col. art., columella-articular bar. 



mal. mck., malleo-meckeUan bar. 



jyian. Mal., manubrium mallei. 



Other abbreviations as in Figs. 3, 4. 



the "columella-articular" bar of the Crocodile lies behind the articular and, 

 as in Sphenodon, it may be homologous with some part of the hyoid cornu, 

 ?'. e., of the second gill arch; while the "malleo-meckelian" bar of the mam- 



