TETRAGONICEPS. 65 



broad, the internal segment much produced (fig. 12), 

 and bearing four long and two short setaa, the longer 

 ones plumose ; second joint small, ovate, and having 

 one long and several small marginal setas ; the basal 

 joint in the male (fig. 13) is not much produced, and 

 has only two spine-like setae. The longer of the two 

 principal tail setaa is a little longer than the abdomen, 

 the other about half as long ; both are minutely plu- 

 mose. Length sVth 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 antennae 

 8-jointed, slender ; posterior long, 3-jointed, with a 

 small 1- jointed 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. II. E 



