IDYA. 171 



Genus 32. IDYA, Philippi (1843). 



(Tisbe, Lilljeborg, Glaus.) 



Cephalothorax broad and somewhat depressed ; 

 abdomen narrow, 5-jointed. Head coalescent with, 

 the first thoracic segment. Anterior antenna 7- or 

 8-jointed, elongated; inferior 3-jointed, with a large 

 4-jointed secondary branch. Mandible long and 

 strongly toothed ; palp 2-branched, basal joint short, 

 branches 1 -jointed, long and slender, setiferous at the 

 apices. Maxilla armed with several slender terminal 

 teeth; palp well developed. First and second foot- 

 jaws nearly alike, uncinate; first 'pair 2-, second 3- 

 jointed. Inner branch of the first pair of feet 2- 

 jointed, clawed; outer branch short, 3-jointed; the 

 three following pairs having both branches 3-jointed. 

 Fifth pair elongated, 2-jointed. 



In the tendency to flattening and lateral expansion 

 of the cephalothorax, and the uncinate form of the first 

 foot-jaws, as well as in the dilatation and peculiar 

 armature of the first pair of feet and the elongated 

 fifth foot, this genus exhibits a distinct departure 

 from most of the Harpacticidse which have been 

 described in the foregoing pages. These characters 

 are even more marked in the next succeeding genus, 

 Scutellidium. The genus Harpacticus, in the struc- 

 ture of the first pair of feet, and Zaus, both in that 

 character and in the lateral expansion of the body, 



