214 ANIMALS OF THE SEASHORE 



ISOPODA 



Isopods differ from Amphipods in that their 

 bodies are flattened dorso-ventrally instead of 

 laterally. In other words, they are flattened on 

 top and bottom. The two groups resemble each 

 other in size and in many details of anatomy. As in 

 the Amphipods there are 6 or 7 pairs of legs. 



Some species of Isopoda may be found among 

 seaweed, under rocks or among woodwork in the 

 intertidal zone, while others swim in the sea either 

 on the surface or at considerable depths. A large 

 number of species are parasitic. 



The following are the most frequently en- 

 countered species of this region. 



Idotea balthica Pallas 

 (/. marina Linne) 



PLATE XXIV. Fig. 11 



The commonest New Jersey isopod; a greenish 

 form about 1 inch long; exceedingly abundant in 

 tide pools and among seaweed in shallow water. 

 It has also been found on the surface of the ocean 

 many miles off shore. Common from Delaware 

 northward; local farther south. 



Livoneca ovalis Say (Sea Louse) 



PLATE XXIV. Fig. 10 



Parasitic on the gills of numerous fish caught 

 along the New Jersey coast. 



