VIII.] 



MONO TREMA TA . 



The hinder sternal ribs are very broad and flat. The 

 Echidna has 16, and the Ornithorhynchus 17 pairs of 

 vertebral ribs ; they do not divide above into head and 

 tubercle, but are attached only to the sides of the bodies 

 of the vertebrae. The last 5 sternal ribs of Echidna, especi- 

 ally E. bruijni, are exceedingly broad and overlap each 

 other. 



I 2 



