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ZOOLOQJ. 
wood. The highest Isopods are Idotcea, of which /. irro- 
ratus is our most abundant species, being common in eel- 
grass, etc., between and just below tide-marks. While the 
Fig. 114. — Gammarus robustus, from fresh water. Much enlarged. 
Isopods are broad and flat, the Amphipods are compressed, 
and the back is usually more or less arched. Such is the 
Fig. 115.— Nehalia bipes. Enlarged 6 times. 
Gammarus, or beach-flea (Fig. 114), found in salt and fresh 
water. 
Order 5. Pliyllocainda. — This group is represented by a 
little Crustacean, with a compressed body, and broad leaf- 
