178 



NEW YORK STATE MUSEUM 



Asellus communis Say 



A s e 1 1 n s communis Say, T. /. c. i8i8. i :427. DeKay. /. c. 1844. 

 p.49. Smith, S. 1. U. S. Fish Com. Rep't for 1872-73. 1874. P-657, pl.i. 

 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. so Asellus communis (After Smith) ^^^^ mottlcd with ycllowish. 



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

 under stones in brooks and ponds everywhere. 



Family ja.nirid.a.ts 

 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.) 



Oniscns marinus Fabricius. Fauna Gronlandica. p. 252. 

 Jaera c o p i o s a Verrill. I.e. 1874. p. 571. 

 Jaera albifrons Harger. /. c. 1880. p. 315, pl.i, fig.4-8. 

 Jaera marina 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 



