MONOTREMES. 
103 
by horny projections or “ cornules/^ There are 19 dorso-lumbar 
vertebrse^ well-marked sternal ribs^ and a pair of large marsupial 
bones placed on the pelvis. 
The two genera of the Order differ in many important respects, 
especially in the shape of the skull. Ornithorhynchus has a 
broad, fiat rostrum, forked in front, which supports the beak, and 
in which first the teeth and then the cornules are implanted ; 
while in Echidna the snout is long, narrow, and toothless, and 
forms merely a long tube for the lodgment of the tongue, as in 
the true Anteaters (Myrmecophaga). In the recently discovered 
Froechidna bruijnii from New Guinea, of which a fine skeleton is 
mounted, the snout is nearly twice as long as the brain-case,' and 
very much curved downwards, while in the common Echidna it is 
much shorter and curved upwards. 
In both Ornithorhynchus and Echidna the anterior limbs are 
more powerfully developed than the posterior, the humerus espe- 
cially being exceedingly thick, and provided with large ridges for 
the attachment of muscles, reminding us of a similar development 
in moles and other digging mammals. 
