HIGHER CRUSTACEA OF NEW YORK CITY 



179 



of yellow and reddish brown. Some are light colored or nearly 

 white, often with two or more transverse bands, forming a striking 

 looking animal. Very fre- 

 quently also shades of 

 light or dark green occur, 

 and the incubatory lamel- 

 lae of the female are often 

 bright green. 



Very common all along 

 the shore below high tide 

 on rocks under seaweeds 

 where their color is pro- 

 tective, or clinging to the 

 undersides of stones or 

 boards. Frequently found 

 in the little pools left on 

 the rocks by the tide. 



Found commonly all 



along the COast. Fig. 5 1 Jaera marina (After Harger) 



5 ONTSCOIDEA 



The tribe Oniscoidea is almost unique among Crustacea in being 

 entirely terrestrial, even the early stages being passed on land. 

 They are oval forms with a more or less depressed body, and the 

 fused head and first thoracic segment are sunk in the second. The 

 first antennae are very small, three- jointed and placed on the front 

 of the head. The second antennae are long and consist of a 

 peduncle of five, and a flagellum of two or three segments. 



They breathe by lamellar gills which are processes of the abdom- 

 inal limbs, and in consequence they require a rather damp 

 atmosphere. 



Their colors are usually dull, brown or dark gray being the pre- 

 vailing tones ; but they are very variable, even in the same species, 

 and color is not to be relied on as a means of identification. In 

 fact a large number of species have been described at various times 

 with color as their main specific character, and many of them have 

 had to be thrown out. 



