64. BRITISH COPEPODA. 
devoid of spines. Inner tail seta twice as long as the 
outer, and about equal in length to the abdomen. 
The inner branches of the swimming-feet in the male 
do not greatly differ from those of the female. Length 
ae! Ol aim nme (C77 warn), 
The localities in which I have met with this species 
are few, but in these it occurs pretty plentifully ; in a 
brackish tidal pond at Westport (Mayo); in a pool 
just above high-water mark, and in ditches amongst 
Utricularia minor, near Clifden (Galway); also in 
brackish pools at Pensarn, Merionethshire. 
2. Mesooura Ropertsoni, nov. sp. Pl. XLVI, figs. 
1—15. 
Animal robust; abdomen not much more slender 
than the thorax, in the female 4-jointed, the last joint 
short, and forming a projecting process at the posterior 
dorsal angle; caudal segments scarcely as long as 
broad ; anal operculum strongly denticulated (fig. 15). 
Anterior antenna much shorter than the first hody-seg- 
ment, slender, 8-jointed (fig. 2), the joints nearly equal 
in length; accessory branch of the posterior antenna 
small, 2-jomted. Posterior foot-jaw (fig. 6) small and 
slender. First pair of feet (figs. 7, 8) very small, 
larger in the male; inner branch composed of two 
nearly equal joints, and only slightly longer than the 
outer branch; inner branches of the second, third, 
and fourth pairs (figs. 9, 10, 11) short, the first joint 
extremely small. Basal joint of the fifth pair very 
