LAND-TOETOISES OF MAURITIUS AND RODRIGUEZ. 157 



curved precoracoid (" acromion ") &c. proving it to be T. inepta. This peculiarity can 

 be parallelled with the case of the corresponding bone of the Rodriguez tortoise. 

 There is no fresh example of T. inepta, var. Boutoni. 



T. inepta. a. b. 



millini. millim. millim. millim. 



Length of scapula (measured from the suture with coracoid) 177 170 



Circumference in its middle 72 72 



Longitudinal diameter of glenoid cavity 40 (worn) 40 



Length of precoracoid (acromion) 95 92 



Length of coracoid . . . . 102 91 



Greatest width of coracoid . . . . 69 broken 



Least circumference of shaft of coracoid . . . . 49 50 



The great amount of variation in the shape of the coracoid in T. triserrata is worthy of 

 special attention. Though all the well-marked specimens in our collection have passed 

 through the hands of Dr. Gimther, he only remarks (I. c. p. 16) that " the coracoid lamina 

 [is] sometimes deeply grooved." The amount of the variations can be well understood 

 by reference to Plate XIII. figs. 1-5. 



The anterior side is sometimes produced into a long spur. The posterior may become 

 straight rather than bowed for the greater portion of its length, as may also the internal 

 edge (' epicoracoid ' region). The shaft may be narrow, or broad and flattened; but it 

 is in the blade that we see the greatest variations. This may be almost smooth, concave 

 above, and gently convex on its inferior surface, as in the typical example (Giinther, 

 pi. xxiv. fig. b), or flat superiorly, with the concave inferior surface traversed by prominent 

 longitudinal ridges, or convex on the upper surface, with the concave lower surface 

 strongly marked by prominent palmated ridges. The interspaces may become so thin 

 as to be more or less perforated. 



The relative measurements of these bones also vary very considerably, as the following 

 table shows : — 



A (type). B. C. D. E. 



millim. millim. millim. millim. millim. 



Length of coracoid 74 75 66 76 76 



Greatest width of coracoid 61 71 63 58 67 



Least circumference of coracoid . . 54 66 47 62 63 



It will thus be seen that while the length averages about the same, the width and 

 circumference of the shaft vary greatly, the normal proportions being, length of coracoid 

 n, breadth n— 9, circumference n — 15. 



The study of all these variations irresistibly calls to mind the remarks of Messrs. A. and 

 E. Newton*, the truth of which has been subsequently confirmed by the latter gentle- 

 man and Mr. J. W. Clark f , in their respective memoirs on the osteology of the extinct 

 Didine bird of liodrignez, as to the wonderful variability of that species. To quote the 

 former : — " There does not seem to be a single bone in the skeleton of Pezophaps solitaria 

 which is not liable to greater or less individual variation of some kind or other, . . . but 



& 



* 



" On the Osteology of the Solitaire or Didine Bird of the Island of Rodriguez, Pezophaps solitaria (Gmel.)." By 

 Alfred Newton, M.A., and Edward Newton, M.A. Phil. Trans. 1SG9, p. 330. 



t " On the Osteology of the Solitaire (Pezophaps solitaria, Gmel.)." By Edward Newton, C.M.G., and John 

 "Willis Clark, M.A., Superintendent of the Museum of Zoology and Comparative Anatomy in the University of 

 Cambridge. Phil. Trans, vol. 106. p. 451. 



21* 



