8 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 120 
mum breadth (fig. 24). From these measurements, the ratios L/B 
rostrum and L carapace/L rostrum were computed. 
Selected data show a hint of bimodality in the Australasian data 
(fig. 34) and a much less definite hint in the American (fig. 38). The 
84 L/B ROSTRUM 
A-AUSTRALASIAN 
a 
NUMBERS 
b 
| 1 IL 
-30 re) 10 20 30 
DEVIATION FROM MEAN XIOO 
4 L/B ROSTRUM 
B-AMERICAN 
3 
wo 
(on 
ld 
m2 
=> 
=>} 
| | 
| 
—30 -20 -10 20 30 
ie) 10 
DEVIATION FROM MEAN XIO0O 
Figure 3.—Frequency distribution histograms showing numbers of Australasian and 
American specimens with varying deviations from group mean L/B ratios. 
small ‘separate’ groups with higher deviations are not distinctive as 
regards sex ratio or size; to simplify analyses, hints of polymorphism 
in L/B rostrum data were ignored. There are no comparable hints in 
L carapace/L rostrum data. 
