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 comimon 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. 51 Jaera marina (After Harger) 



5 ONISCOIDEA 



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 ustfklly 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. 



