1/ NEW YORK STATE MUSEUM 



Asellus communis Say 



A s e 1 1 u s communis Say, T. /. c. 1818. 1 1427. DeKay. /. c. 1844. 

 p. 49. Smith, S. I. U. S. Fish Com. Rep't for 1872-73. 1874. P-657, pl.T. 

 fig.4. Richardson. /. c. 1901. p. 551. 



A fresh-water form. Body 

 with sides parallel. Anten- 

 nulae short and flagellum 

 with several segments. An- 

 tennae more than half length 

 of body. First pair of legs of 

 male chelate, last three pairs 

 longer than the preceding. 

 Pleon large, squarish and in 

 one piece; uropoda elongated 

 and flattened. 



Length 15 mm, breadth 5 

 mm. Color brown, spotted 



Fig. 50 Asellus communis (After Smith) an( j mott l e d with yellowish. 



The only fresh-water Isopod found in New York city. Occurs 

 under stones in brooks and ponds everywhere. 



Family J^VISIIRIDAE, 



Marine forms, much like Asellidae. The first pair of pleopoda 

 in the female are a large opercular plate. To the corresponding 

 plate of the male the copulatory appendages are joined laterally, 

 succeeding pairs delicate. 



Jaera marina (Fab.) 



O n i s c u s m a r i n u s Fabricius. Fauna Gronlandica. p. 252. 

 Jaera c o p i o s a Verrill. /. c. 1874. p. 571. 

 Jaera albifrons Harger. /. c. 1880. p.3i5, pl.i, fig.4-8. 

 Jaera m a r i n a Richardson. /. c. 1901. p-554- 



Body oval, slightly more than twice as long as broad. Anten- 

 nulae short, antennae more than half the length of body and with 

 multiarticulate flagellum. Pleon in one piece, semicircular, with 

 short uropoda rising from a notch in the end. 



Length 5 mm, breadth 2 mm, males about one third shorter and 

 somewhat narrower. Color very variable, slaty gray with blotches 



