66 On the Martinet a Tinamou. 



diverticula get less and less marked until we arrive at the 

 apex, which is quite smooth. These diverticula are the 

 " claw-shaped protuberances " of Mr. Hudson, and this de- 

 scriptive term was by no means badly chosen; each diver- 

 ticulum tapers towards its extremity and is bent inwards, 

 thus assuming a decidedly claw-like shape. 



The appearance of the interior of the caecum is illustrated 

 in fig. 3, p. 65, and is not by any means unlike the reticulum 

 of a ruminant's stomach. Each of the diverticula is marked off 

 by a raised valvular ridge. Towards the apex of the caecum, 

 where the diverticula are less prominent as such, the valvular 

 ridges are quite as well marked as they are posteriorly; 

 they are, indeed, rather more conspicuous, though this is 

 not very well shown in the figure, which, however, represents 

 the caecum flattened out. An interesting peculiarity about 

 these valvular projections is, that towards the apex those run- 

 ning transversely, or nearly so, to the long axis of the caecum 

 get to prevail over those running longitudinally. The effect 

 of this is to produce a spiral arrangement, and the last inch 

 of the caecum (at any rate in one specimen, where it was 

 very obvious) was marked by a simple spiral valve, all trace 

 of the connecting ridges marking the surface out into areas 

 having vanished. 



There is here an interesting resemblance to the Ostrich *, 

 which may possibly be more than a mere superficial likeness. 

 In any case the remarkable form of the caeca of Calodromas 

 elegans is due to the presence of these valve-like folds, which 

 produce constrictions on the outer surface, between which 

 the caecum tends to bulge out. Posteriorly the intervals 

 between the folds are so greatly produced into external pro- 

 tuberances that, until a dissection is made, one is tempted 

 to regard the protuberances as regular diverticula of the 

 caecum, which they are, strictly speaking, not, any more 

 than the intervals between the spiral valve of the Ostrich's 

 caecum, or the sacculations of the mammalian caecum. It 

 is perhaps a little difficult to make such a distinction, but I 

 regard the folds as having appeared first and as having, in a 

 way, caused the appearance of the diverticula. 



* See Sir Everard Home, ' Comparative Anatomy,' vol. i. 



