318 A. E. TVrr/7/ Decapod Crustacea f 



can be seen, at a distance, clustered together mi tin- exposed dill'-. 

 for their bright red cliehe and large si/.e render llicin very con-picn- 

 ous, but they usually run away rapidly or plunge int> tin- water 

 when approached. 



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

 colors by natural selection, for in Bermuda and mo-t ,,t her region- 

 where it abounds the colors appeal' not at all protective, unless at 

 night, but (piite the reverse.- Possibly the colors were originally 

 developed in some region where its surrounding were dill'erent, 

 and red colors prevailed among the rocks : but its color-, may l>e noc- 

 turnally protective. At present the Species lias -pread all around the 

 world in tropical seas, and it does not much need color protect ion. 

 owing to its watchfulness and ability, yet it i- often killed by >ea -fowl, 

 and also by the Ortnjiiix. 



The colors are somewhat \ariable. Some are much redder than 

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

 thickly and irregularly mottled and spotted \\ith bluish and -raxi-h 

 white: the lighter color predominating in the radial grooves. 

 Chelipeds with the cliehe and carpal joint- bright dark red, white 

 at ti]s of claw-; 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. In-neat h, orange red and light blue : 

 branchial areas, oral organ-, and area in front of mouth m-l]y light 

 blue; sternum and under -ide of le--. orange and blue. 



The sexes differ very little in si/.e 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 spot- 

 round and about 1 to ^ mm in diameter. The chela' of the tnales 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. 



