YERKES. — VARIATION IN THE FIDDLER CRAB. 



427 



were collected at three 

 different times (75 July 

 24, 125 August 17, and 

 200 August 24), of 

 which the first and last 

 were separated by over 

 three weeks, this is not 

 improbable. But as I 

 have no data on ecdysis, 

 it is impossible to settle 

 this point. 



2. Median length. 

 This is the second larg- 

 est dimension taken. It 

 is slightly more variable 

 than the frontal breadth. 

 The polygons No. 2R 

 and 2L represent simi- 

 lar distributions, with a 

 greater frequency, how- 

 ever, at the mode of the 

 Rights, as in the frontal 

 Breadth, indicating less 

 variability than in the 

 Lefts. 



8. Right margin. It 

 should be remembered 

 that No. 3R and 3L are 

 not strictly comparable 

 because of the asymme- 

 try of the animals. The 

 polygons have been 

 placed together because 

 they represent identical 

 measurements. Compar- 

 ison should also be made 

 of No. 3R with 4L, the 

 polygons for the margin 

 on the side of the great 

 chela of the Rights and 



Polygon No. 2R. 



Polygon No. 2L 



