No. 26.] ARTHROSTRACA OF CONNECTICUT. 33 



extent in preservatives that at best only a few spots of pigment 

 of a chocolate brown or black remain. 



The usual color is whitish or grayish but a few of the native 

 species exhibit very characteristic pigmentation. Leptocheirus 

 pinguis, for example, retains its dark chocolate spots even after 

 years in alcohol. Unciola irrorata is mottled with bright crimson. 

 Jassa marmorata is of a reddish ground color, interrupted by large 

 lighter spots. 



Many species also exhibit great variations in coloring. 

 Amphithoe longimana may vary from bright green to bluish 

 green, or nearly colorless, and also from light to dark reddish 

 brown. 



According to Holmes (Biol. Bull., vol. 2, p. 181, 1902) the 

 color of some individuals is by no means constant In Amphithoe 

 longimana, the species studied by Holmes, the color is due 

 especially to the pigment cells although the color of the blood 

 and tissues, the contents of the alimentary canal, and the color 

 of the reproductive glands also affect that of the body, as seen 

 by the naked eye. In one specimen the general blue color of the 

 blood and tissues after five days had disappeared, the green be- 

 coming more nearly like the typical green of other forms, and by 

 the ninth day the tissues were whitish. This whitening took 

 place in spite of the fact that abundant quantities of green algae 

 were consumed. 



The most important factors in determining the color changes 

 in Amphithoe longimana are the reddish-brown pigment spots 

 which are scattered all over the body and on most of the append- 

 ages, especially near the proximal end. These pigment spots 

 change very slowly, generally requiring several hours to effect a 

 change from the expanded to the contracted condition. 



HABITAT. 



The Amfhipoda are exclusively aquatic in their habitat, and 

 very generally they are marine. It is only among the Orchestiidae 

 that there is an approach to a terrestrial habitat. Talorchestia 

 longicornis occupies a zone of the beach a short distance above 

 high-water mark but sinks its burrows to a depth at which the 

 sand is always moist. Orchestia palustris and O. agilis also live 

 near high-water mark, the latter occupying a lower zone than the 

 3 



