412 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



similar to those of D. palustris. The first pair of swimming 

 feet have the inner branches composed of two joints, as in 

 D. palustris, bnt the first joint is proportionally shorter 

 and the second joint longer and narrower than in that 

 species. The second joint is furnished with two setse on 

 the inner margin and two at the apex ; the outer branches 

 are armed like those of D. palustris. The second, third, 

 and fourth pairs of swimming feet resemble those of 

 D. palustris. The fifth pair of feet have the basal joints 

 only slightly produced. The apex of the .'joints is irregu- 

 larly angular, and furnished with four setae placed equi- 

 distant from each other. The outer branches are sub- 

 quadrangular in shape, being longer than broad. They 

 are furnished with one setae on the outer margin near the 

 apex, and four on the apex, the second from the exterior 

 being shorter than the other setae (fig. 22). Caudal furca 

 slightly longer than the last abdominal segment. 



Remarks. — This species at first sight is not unlike 

 Delavalia palustris, but on examination is easily dis- 

 tinguished from it by the proportional lengths of the joints 

 of the antennules, the structure of the first feet, and also 

 of the fifth feet. 



Delavalia minuta, n. sp. Plate III., figs. 15-18. 

 Occurrence, Nos. 1, 3, 4, 19. 



Description of the Female — 'Length '48 mm. Some- 

 what similar in shape to the last species, but smaller and 

 with rather longer caudal furca. The antennules are 

 eight-jointed, and resemble those of D. robusta, Brady. 

 The formula shows the proportional lengths of the joints. 



Proportional lengths of the joints - 5 8 5 4 4 4 3 5 

 Number of the joints - - - - 1 Z~~ 3 4 5 6 7 8 



The first pair of swimming feet have the inner branches 

 two-jointed, like those of D. inopinata, but the basal joint 

 is proportionally longer, and the second joint shorter and 



