106 SKELETONS OF THE McmOTREMES, 



a point that can only be settled through an examination of 

 an adult specimen in the flesh. Personally, I very much 

 doubt that the bones are closely adpressed to the cervical 

 ribs as in the skeleton 2639 (see Fig. 11 for the Echidna). 



**In the Monotremata the Ornithorhynchus" says 

 Flower, "has a broad presternum, with a small, partially 

 "ossified pro-osteon in front of it; three keeled mesosternal 

 "segments, which commence to ossify in pairs, and no xiphi- 

 "sternum, which in E. hruijni consists of three metameric 

 "portions. 



"The T-shaped bone, interclavicle or episternu7}i in front 

 "of the presternum, which connects it with the clavicle and is 

 "often completely fused with it, appears to have no homo- 

 "logue among the other Mammalia, and belongs more pro- 

 "perly to the shoulder-girdle than to the sternal apparatus" 

 (pp. 104, 105). 



The Vertebral Column and Ribs: — Judging from the 

 accounts of various anatomists, the vertebras and the ribs 

 in the Echidnas and the Duckbill are subject, with respect 

 to number, to very considerable variation in different indi- 

 viduals. C^) 



In the work of G. P. Frets, cited above, there are tables 

 presenting the great variation in the number of vertebrae 

 in the Echidna — and so it goes for other authorities. 



Flower gives us the following table (p. 89) : — 



MONOTREMATA. 



Owen makes a brief statement to the effect that "both 

 "the genera have twenty-six 'true vertebrae,' of which seven 

 "are cervical; but the Ornithorhynchus has seventeen and 

 "the Echidna sixteen dorsals, the lumbar vertebrae being 

 "three in the latter, and reduced to the lacertian number two 

 "in the Ornithorhynchus,'' to which statement he makes no 

 exceptions (p. 316). 



(7) BROWN, R., M.B., B.Sc— "Note on an Echidna with eight vertebrae." 

 Proc. of the Linn. Soc. of New South Wales, 1900. Vol. XXV., Syd- 

 ney, 1901. One cut. "Dorsals vary from 14 to 17 ; lumbars 2 to 4 ; 

 "sacrals 3 to 4 ; caudals 10 to 14." This authority also gives some 

 important notes oil the ribs of the monotremes. 



