70 FRANK BLAIR HANSON 



animals have both the inscriptiones tendineae and also a complete 

 sternal and costal apparatus. If the latter be the derivative of 

 the former, why this persistence of the two structures side by side 

 in nearly all groups above the lower Urodeles? 



3. Reptiles 



Fossil reptiles constitute the next group in which we have 

 looked for a sternum or any part of one which either originates 

 independently of the ribs or which has intimate relations with the 

 shoulder-girdles. The author has studied figures and plates of 

 much of the recent work done on fossil reptiles, of which the in- 

 vestigations of Credner ('81-'93), Gregory ('15), Seeley ('92, '94), 

 Woodard C98), and Zittell ('00, '13) are typical, and, in addition 

 has examined a number of mounted specimens in the U. S. 

 National Museum. It may be said in general that in those 

 skeletons which have the shoulder-girdles preserved there is a 

 strong tendency for the coracoids to grow around the side of the 

 body ventrally, though never meeting in the midline, for the soft 

 epicoracoids are not preserved, and that the coracoids are enor- 

 mously developed in size. 



Gunther ('67), Schauinsland ('00), and Howes and Swinnerton 

 ('01) worked on the development and anatomy of that primitive 

 and now almost extinct reptile from New Zealand, Hatteria 

 punctata or Sphenodon. In one of Gunther 's figures the 

 shoulder-girdle and sternal bars are shown in their natural 

 relation at that stage. The coracoids do not have a large ventral 

 extension, but are capped on their medial ends by slender proc- 

 esses which later unite to form the presternum. Three pairs of ribs 

 reach each sternal bar, so that the sternal and costal connections 

 are much too far advanced for any statement as to the origin 

 of the sternal bars in Sphenodon. So far as I am aware, this is 

 the youngest stage of the Sphenodon sternum figured in the 

 literature. 



From the condition in the embryos of living reptiles, as well as 

 in many of the adult species, it may be assumed that in the early 

 condition of fossil reptiles the coracoids were in intimate relation 

 to the sternum. 



