29 2 BULLETIN OP THE BUREAU OF FISHERIES. 



in all individuals, thus forming a definite color scheme. The tail is spotted with yellow- 

 ish ocelli, and the posterior margin of each segment is edged with yellow or orange. 

 The lower angles of the segments are marked with dark bluish or greenish tints and 

 sometimes additional colors. The pleopods are usually orange, about half the area 

 being covered by a black blotch. The legs are striped longitudinally with blue. The 

 ventral surfaces of the body are cream colored or light yellow, and the thoracic sternum 

 is marked with irregular, radiating stripes. The tail fan is crossed by bands of orange, 

 yellow, and black and is fringed with white. 



The coloration of the young differs from that of the adults in some respects. The 

 colors of the carapace in very small individuals are arranged in transverse bands, usually 

 three, the middle one being dark. The antennae are frequently ringed with alternate 

 light and dark bands, and the legs are ringed with blue. 



Panulirus argns, like other species of the same genus, varies considerably in color. 

 Coloration, apparently, is correlated with habitat, two groups of coloration being dis- 

 tinguished, one consisting of lightly colored individuals and the other of darkly colored 

 individuals. The range in color of the former group is from light gray and tan to shades 

 of green and light brown, while the second group varies from shades of red to deep 

 browns and blues. 



Large catches have been observed in the market, and it was noted, when it was 

 possible to learn where they had been caught, that the lightly colored spiny lobsters 

 came from places where the bottom was known to be lightly colored, and the darker indi- 

 viduals came from places where the bottom is covered by growths of sea fans and sponges. 

 Such growths have been raised occasionally with the traps when it was noted that the 

 color is similar to that of the spiny lobsters taken. Large numbers of spiny lobsters 

 which have been caught in a given area have been found to vary only in slight degree 

 in this respect. 



Depth of water does not influence the color except indirectly, since the growths of 

 sea fans and sponges are sometimes heavier in deep water and lightly colored bottoms 

 are more generally found in shallow water. A migration, therefore, from one kind 

 of habitat to another is indicated when spiny lobsters of different colors are caught in 

 the same trap. 



DIFFERENCES BETWEEN YOUNG AND ADULTS. 



The young of both sexes possess antenna? which are longer in proportion to the body 

 than they are in the adults. The spines on the carapace are better developed in the 

 young, and very small individuals have on the carapace numerous setae which gradually 

 disappear with age. Specimens measuring 2 inches in length of carapace do not possess 

 these setae. The spines on the carapace of very large spiny lobsters are replaced fre- 

 quently with tubercles, only those on the anterior parts of the carapace remaining acute. 



Adolescent males, while often nearly as large as the adults, differ from them in the 

 development of the second pair of legs and the size and shape of the second dactyl. 

 The dactyl of the adult male is rather slender and curved and provided with a brush 

 of long setae which is not as well developed in the young or adolescent males. The 

 second dactyl of adolescents is stouter and less curved and the setae are shorter than 

 those of the dactyl of the adult. 



