GENEEA UROTHOE AND UEOTHOIDES. 23 



Urothoe breticornis, Sp. Bate. (Plate III. ; Plate IV. C.) 



1863. Urothoe brevicornis, Sp. Bate, Brit. Mus. Catal. Amph. Crust, p. 116, pi. xx. fig. 1. 

 1863. „ „ Bate & Westwood, British Sess. Crust, vol. i. p. 198, woodcuts. 



1879. „ marinus, Stabbing, Sess. Crust. Devon., Trans. Devon. Assoc, vol. xi. p. 519. 



Eostrum forming an obtuse angle, but with a little acute point between the upper 

 antennte. Second pleon-segment with the plumose setae large and numerous, the 

 produced point of the postero-lateral angles minute. 



Eyes very conspicuous in the male, approaching one another very closely. 



Upper antennw nearly as in Urothoe marinus. In the adult male specimen the first 

 joint of the peduncle was decidedly longer than the second, and the principal flagellum 

 had seven joints, the accessory flagellum being more than half its length, with six joints, 

 of which the last was minute. 



Lower antennm. In the adult male peduncle nearly as in Urothoe marinus, but in the 

 fourth joint the brush of hairs not passing round the distal margin ; the spines twenty- 

 two in one row, five in the other, the setae more numerous ; the fifth joint rather longer 

 than the fourth, with nine calceoli on one side, and eight long plumose setae on the 

 other ; the flagellum not once and a half as long as the peduncle, having twenty-three 

 or twenty-four joints, with a calceolus to each of the first three or four, and then on 

 alternate joints for some distance along. In the female the fourth joint is longer than 

 the fifth, and has twenty-five spines in one row, seven in the other, with numerous long 

 serrate setae near the straight inner border, and a group of about a dozen near the 

 produced distal corner of the convex side; the fifth joint has thirteen spines along the 

 convex border, with a group of eight long setae near its distal end, and along the other 

 border some fifteen long setae ; the two-jointed flagellum is shorter than the last joint 

 of the peduncle ; the first joint has ten long setae round the distal half, and three spines 

 on one margin ; the little second joint is about a quarter the length and not half the 

 breadth of the first, and is tipped with two slender setae several times its own length. 

 Both in male and female the fourth and fifth joints of the peduncle have some little 

 stiff setae or cilia, which are strongly plumose, and appear as if twisted at the centre. 



Upper lip with a smoothly rounded margin to the principal plate, except that in the 

 centre a little space is marked off by a small notch on either side, the tract so marked 

 off being distally smooth, but furry on the sides. The inner plate appears to have a 

 quite smooth margin not reaching quite to the distal margin of the outer plate. The 

 structure of this lip seems to be tolerably uniform in all the species. 



Mandibles as in Urothoe marinus, except that the third joint of the palp has nearly 

 two thirds of the inner margin clear of spines. ' 

 Lower lip as in Urothoe marinus. 



First maxillw. The inner plate with three plumose setae on the apex ; outer plate as 

 in the other species ; palp with the first joint rather longer than the second, the second 

 with the usual three setae on the apex. 



