19G DUBLIN UNIVEESITY 



LUCASITJS (n. g.). 



Body flattened ; head transverse ; no frontal lobe ; lateral lobes well 

 marked, arising from third segment beneath orbits. 



Internal antennae three-jointed. 



External antennae : peduncle, second articulation squared, lobed ; 

 fifth, scarcely broader than filament; tige two-jointed; articulations 

 conical, very unequal in length. 



Cephalothorax : coxa) well developed. 



Abdomen : coxae of first and second somites obsolete ; coxae of third, 

 fourth, and fifth, narrow, curved backwards. Telson (last somite) : coxae 

 nearly obsolete. 



Posterior pleopods (false feet) arising from inner margin of telson. 

 Peduncle nearly completely concealed by last ring ; quadrilateral. Ac- 

 cessory lobe well marked, arising from base of peduncle. Accessory 

 filament slender ; blunted at the apex. Ischium trigonal, uncovered for 

 two-thirds its length. Species : L. myrmecophilus, 



Lucasius myrmecophilus (Lucas* sp.). 



Synonyms: Porcellio myrmecophilus (Lucas, "Revue de Zoologie"). 



Body covered sparingly with tufts of hair shining, head granu- 

 lated. Granulations continued down on first, second, and third cephalo- 

 thoracic segments. Internal antennae inconspicuous. External antennae : 

 peduncle hairy, five-jointed*. First articulation short and linear ; second, 

 squared, twice the length of first ; third, short and triangular ; fourth, 

 triangular ; fifth, nearly twice the length of fourth ; the superior margins 

 of all the articulations deeply emarginate. Tige : first joint extremely 

 short ; second joint equal to second, third, fourth, and fifth of peduncle, 

 conical, surrounded by regular circlets of hairs. 



Telson triangular, apex acute, sides straight, a shallow pit mark- 

 ing its upper surface. Sparsely covered with hairs, but shining. Pos- 

 terior pleopods covered with scattered hairs. Basis flattened, quadrila- 

 teral, hairy. Accessory lobe short. Accessory appendage scarcely 

 attaining apex of basis, stout, hairy, blunt-pointed. Ischium trigonal, 

 hairy. 



Habitat : the nests of Myrmica testaceo-pilosa (Luc). 



Locality : Medcah, Algeria, Africa, where it was discovered by M. 

 H. Lucas, Membre de la Commission Scientifique l'Algerie, after whom 

 I have named the genus. 



