YERKES. 



VARIATION IN THE FIDDLER CRAB. 



419 



report, therefore, represents only a fragment of what was planned, and 

 what the complete solution of the suggested problems demands. 



III. Methods and Material. 



The following measurements were made : — 



1. Frontal Breadth, the distance between the anterior marginal points 

 of the carapace (Figure 1, FB). 



B 



Figure 1. Dorsal aspect of carapace. BA, right marginal length. FB, 

 frontal breadth. ML, median length. 



2. Median Length, the maximum length of the carapace in the median 

 plane. (Figure 1, ML). 



3. Right Marginal Length, the distance from the right anterior mar- 

 ginal point of the carapace to the posterior end of the lateral ridge, just 

 above and between the fourth and fifth legs (Figure 1, BA). 



4. Left Marginal Length. 



5. Meropodite of the Right Chela, the distance between the articula- 

 tions on the anterior face. The proximal point of measurement, i. e. 

 the articulation between ischiopodite and meropodite, is on the anterior 

 ventral surface, and therefore does not show in Figure 2. 



6. Carpopodite of the Right Chela, the distance between the anterior 

 articulations (Figure 2, CL). 



7. Propodite of the Right Chela, the distance from anterior articula- 

 tion with carpopodite to articulation with dactylopodite (Figure 2, PL). 



