vii.] EDENTATA. 103 



by synovial articulations with the segment before and behind, 

 and has at either end an upper and lower hollowed surface, 

 which, with the corresponding surfaces on the contiguous 

 segment, form articulating facets for the double-headed 

 sternal ribs. This mode of articulation curiously resembles 

 that at the vertebral end of the rib. The xiphisternum is 

 rather long and simple. 



In the small Tree Anteater (Cycloturus didactylus) the 

 presternum is very broad and trilobate, sending out lateral 

 expansions behind the attachment of the clavicles to meet 



mtt 



FIG. 43 Side view of three mesosternal segment* of a young Anteater (Myrnte- 

 cofHaga t<iman<iua\ showing the mode of articulation of the sternal rib (jr). 

 copied from Parker's figure, nisi thi upper or inner surface of the mesostcrnal 

 segment ; ty the synovial articulation between the segments. 



the first pair of ribs. The hinder, narrow part of the manu- 

 brium is segmented off from the larger anterior part, and 

 resembles a mesosternal segment ; but it is in front of the 

 attachment of the second pair of ribs. The true mesosternal 

 segments are six in number, of nearly equal width, high, 

 rounded above, and con-. pressed below, with a synovial 

 cavity between each. The sternal ribs are articulated by a 

 single oval condyle. The xiphisternum is long, stout, and 

 styliform. 



