362 KEY. A. M. NOEMAN AND ME. G. S. BEADY 



posterior antennae have their base of moderate thickness ; and the 

 long seta of the three-jointed ramus is ciliated on one side; the 

 remaining setae have a spine at the end of their first joint. The 

 most marked character, however, consists in the anterior antennas, 

 which are somewhat club-shaped, sub-truncated, rounded at the 

 extremity, and instead of having the long tentaculiform setae of 

 If. laticornis, are only furnished with fine hairs distributed round 

 their extremity; but arranged here and there, throughout the 

 length of the antennae, are tufts or semi-verticils of fine hairs, 

 these are more evident on the anterior margin, but are present 

 also on the sides ; on the posterior margin there are no hairs 

 except near the distal extremity. Abdomen of the same form 

 as that of the last species ; the margin, instead of being denti- 

 culate, is furnished with hairs which are very minute, except 

 towards the small terminal claws, where they become much larger 

 and more conspicuous. Length, aVkh of an inch, this being by 

 far the largest of the three species of the genus. 



The only locality at present known for this new species is a 

 slowly-running stream at Ashburn, Sunderland, where it was 

 found by G. S. B., in 1864. 



3. Maceothetx eosea, {Jurine.) PI. XXIII, figs. 1-3. 



1820. Monoculus roseus, Jurine. Histoire des Monocles, p. 151. 

 PI. XY, figs. 4, 5. 



1850. Macrothrix roseus, Baird. Brit. Entomostraca, p. 104. 



1853. Macrothrix rosea, Lilljeborg. De Crust, ex Ord. tribus 

 Cladoc. Ostrac. et Copep., p. 47. PL IY, figs. 1, 2 ; 

 and PI. Y, fig. 1. 



1860. Macrothrix roseus, Leydig. Xaturges. der Daphniden, 

 p. 192. 



Carapace narrower than in the last two species ; the central 

 point at the posterior extremity more produced ; dorsal margin 

 not serrulate, but towards the posterior extremity furnished with 

 a few minute distant spines ; ventral margin denticulate and 

 ciliate, cilia very long. Anterior antenna? long and narrow, not 



