318 A. E. Verrill — Decapod Crustacea of Bermuda. 



can be seen, at a distance, clustered together on the exposed cliffs, 

 for their bright red chelse and large size render them very conspicu- 

 ous, but they usually run away rapidly or plunge into the water 

 when approached. 



It is not easy to explain how it could have acquired such bright 

 colors by natural selection, for in Bermuda and most other regions 

 where it abounds the colors appear not at all protective, unless at 

 night, but quite the reverse. Possibly the colors were originally 

 developed in some region where its surroundings were different, 

 and red colors prevailed among the rocks ; but its colors ma}^ be noc- 

 turnally protective. At present the species has spread all around the 

 world in tropical seas, and it does not much need color protection, 

 owing to its watchfulness and agility, yet it is often killed by sea-fowl, 

 and also by the Octopus. 



The colors are somewhat variable. Some are much redder than 

 others. A large one, in life, had the carapace very dark brown, 

 thickly and irregularly mottled and spotted with bluish and grayish 

 white ; the lighter color predominating in the radial grooves. 

 Chelipeds with the chelte and carpal joints bright dark red, white 

 at tips of claws ; basal joint pale blue, red at the ends. Legs dark 

 reddish brown above, thickly blotched with bluish white, and 

 bright red at each joint. The posterior pair of legs are tinged with 

 orange on the lighter parts. Beneath, orange red and light blue ; 

 branchial areas, oral organs, and area in front of mouth mostly light 

 blue ; sternum and under side of legs, orange and blue. 



The sexes differ very little in size or color. The larger males are 

 often brighter red than the females, but not constantly so. The 

 ground-color is often blood-red with most of the small yellow spots 

 round and about 1 to 2""^ in diameter. The chelse of the males are 

 usually a little larger than those of the females. The right and left 

 differ but little in the male. Some females taken by us in April, 

 1901, carried eggs. 



This species also varies considerably in its form and the propor- 

 tions of length to breadth of the carapace, as shown by the following 

 table of measurements. The front is often nearly or quite perpen- 

 dicular, but in other cases more or less oblique. 



