TETRAGONICEPS. 65 
broad, the internal seement much produced (fig. 12), 
and bearing four long and two short sete, the longer 
ones plumose; second joint small, ovate, and having 
one long and several small marginal setz; the basal 
joint in the male (fig. 13) is not much produced, and 
has only two spine-like sete. The longer of the two 
principal tail setz is a little longer than the abdomen, 
the other about half as long; both are minutely plu- 
mose. Length 3!;th of an inch (68 mm.). 
This I know only from Irish specimens. It occurred 
in gatherings taken by Mr. Robertson and myself in 
Lough Enask and Lough Arddery (two of the small 
lakes of Connemara), and abundantly in a brackish 
ditch near Newport, Co. Mayo, Ireland, where it was 
found by Mr. Robertson, after whom I have much 
pleasure in naming it. 
Genus 16. TETRAGONICEPS, nov. gen. 
Animal elongated, cylindrical; head consolidated 
with thorax; abdomen elongated. Anterior antennse 
8-jointed, slender; posterior long, 3-jointed, with a 
small 1-jomted inner branch. Mandible-palp slender, 
2-branched; maxillar palp moderately developed ; 
second foot-jaw forming a prehensile clawed hand. 
Inner branch of first pair of feet elongated, 2-jointed, 
outer 3-jointed ; second, third, and fourth pairs with 
the outer branch long and 3-jointed, the inner branch 
2-jointed ; fifth pair 1-branched. 
This genus is well characterised by the very long 
VOL. Il. E 
