8 Prof. W. F. R. Weldon. Certain [Mar. 3, 



Fig. 4. 



r = 0-81, then a deviation of carapace length equal to mQ c mm. is 

 associated with a mean deviation of the post-spinous portion equal to 

 OSlmQps mm. ; and from the values of Q c and Q ps given above, the 

 ratio 0'81raQ F : mQ c is equal to 0*62. In the same way a deviation 

 of mQp S mm. in the post-spinous portion of the carapace is associated 

 with a mean deviation of the whole carapace equal to 0-81 mQ c mm. ; 

 the ratio 0*81 mQ c : mQ ps being equal to 1-05. 



From the fundamental formula given above on p. 3, 



0- 62 Q> 



1- 05 Q a c ' 



