462 Raymond — Trilobite Retaining Color-Markings. 



being a little gastropod, Holopea harpa (Hudson), 

 described by the writer from the Chazy. 1 



I am not sufficiently familiar with the colors of recent 

 crustaceans to make any extensive comparisons, but it 

 appears that those of the deep sea are often brightly 

 colored, but without markings, those inhabiting caverns 

 and other dark places are very pale to dead white, 

 whereas those in the shallow photic waters are of many 

 colors, and often mottled, banded, striped and shaded. 



Fig. 1. 



Fig. 1. — A pygidium of Anomocare vittata, retaining color-mark- 

 ings. X 3. 



Pelagic Crustacea usually have pigmentless tests, and 

 owe their brilliant colorations to chromatophores, circu- 

 lating fluids, or the structure of their shell. The present 

 specimen, as was to be expected, falls in ivith the group 

 in the shallow waters. 



The shells of the branchiopods and copepods do not 

 commonly contain pigments but among the amphipods 

 and isopods are to be seen some patterns which are simi- 

 lar to the one on this trilobite. Delia Valle in particular 

 has published colored figures of Amphipods 2 showing 

 strongly contrasted transverse bands of pink, alternating 

 with yellow, white, or green. 



According to Newbigin, 3 red lipochromes are the 

 dominant pigments in the Crustacea. Where the shell 

 is thin, red and pink prevail, as in the deep sea crus- 

 taceans. When much lime is present in the shell an 

 orange tint is often produced. This being the case, and 



1 The Nautilus, 19, p. 101, 1906. 



2 Gammarini del Golfo di Napoli, 1893, pis. 3-6. 



3 Colour in Nature, London, 1898, p. 128. 



