DELAVALIA. 43 



1. DELAVALIA PALUSTRIS, Brady. PL L, figs. 1 8. 



Delavalia palustris, Brady. Nat. Hist. Trans. Northumberland 

 and Durham, vol. iii, p. 134, pi. v, figs. 

 10-15 (1868). 



Rostrum short, broad, somewhat retuse at the apex, 

 and having two minute lateral setas. Anterior antenna 

 (fig. 2) shorter than the first body-segment, rather 

 densely hairy on the distal half, and devoid of a 

 flagellum : second joint of the posterior antenna (fig. 3) 

 fringed with a series of spine-like hairs on the outer 

 margin ; inner branch composed of two long, slender 

 joints. Mandible-palp (fig. 4) large, all the joints long 

 and slender; one of the terminal setae of the main 

 branch excessively long. First pair of swimming-feet 

 (fig. 6) short, the two branches nearly equal in length ; 

 inner branch 2-jointed, the second joint being slender 

 and about twice as long as the first : each branch 

 bears only two slender and moderately long spine-like 

 setae at its apex. Basal joint of the fifth pair (fig. 8) 

 almost obsolete, terminal joints distant, broadly ovate, 

 the distal extremity fringed with six subequal and not 

 very long setae. Anal operculum protected by two 

 curved lines of teeth. Caudal segments more than 

 twice as long as broad, distant, and slightly divergent. 

 Inner (or longer) tail seta about as long as the 

 abdomen ; outer seta half the length of the inner. 

 Length y^th of an inch ('85 mm.). Male unknown. 



The only locality in which I have as yet found this 

 species is at the mouth of the Seaton Burn, Northum- 



