No. 26.] ARTHROSTRACA OF CONNECTICUT. 233 



This is a very abundant species, occurring everywhere in 

 brooks and ponds, under stones, and crawling over the stems of 

 water weeds. It is very tenacious of life; a single specimen 

 survived in a vial containing a small amount of clean water for 

 a space of three months, with nothing to feed on except possibly 

 the cork of the vial which lay on its side for part of the time. 

 This specimen, together with several others about 5 mm. in length, 

 was brought to me by Mr. S. C. Ball who found them in water 

 drawn from a faucet in New Haven in 1910. 



JANIRIME. 



General appearance like that of the Asellidae but with the 

 lateral margins of head always lamellarly expanded. Eyes, when 

 present, subdorsal. 



First antennae sometimes well developed, with multiarticulate 

 flagellum, sometimes very small and with rudimentary flagellum. 

 Second antennae always longer than first pair, with peduncle of 

 six segments and with small scale-like appendage external to the 

 third joint. 



Mouth parts normal. 



Legs subequal in length, with dactyls bi- or tri-unguiculate ; 

 first pair sometimes differing from others in being prehensile. 



First pair of pleopods in female in form of single, large oper- 

 cular plate; in male constituting the median piece of the com- 

 pound operculum, the lateral pieces of which are formed by the 

 copulatory organs. Uropods biramous. 



Jaera marina (Fabricius). 



1853. Jcera copiosa, Stimpson, Smithson. Contrib. Knowl., 

 vol. 6, p. 40, pi. 3, fig. 29. 



1868. Jam albifrons, Bate and Westwood, Brit. Sess. Crust., 

 vol. 2, p. 317. 



1874. Jeer a copiosa, Harger, ' Rept. U. S. Com. Fish, for 

 1871-2, p. 571. 



1880. ]ara albifrons , Harger, ibid., for 1878, p. 315, pi. i, 

 figs. 4-8. 



1899. Jcera marina, G. O. Sars, Crust. Norway, vol. 2, p. 

 104, pi. 43. 



