ON BOSMLNIDiE, MACROTHKICIDJE, ETC. 361 



1860. Macrothrix laticornis, Leydig. Naturges. der Daphniden, 

 p. 193. 



Carapace ovate, most produced in the middle of the posterior 

 extremity ; dorsal margin having a slight sinuosity about the 

 middle, after which it sweeps with a well-arched curve gradually 

 to the central point at the posterior extremity, where the divi- 

 sion of the carapace commences ; the dorsal margin is finely 

 serrulated throughout the whole of the posterior half; ventral 

 margin well arched, fringed with long cilia (except on the hinder 

 portion), gradually curving to meet the dorsal margin at the cen- 

 tral posterior point, so that there is no trace of any infero-posteal 

 angle. Head somewhat flattened on the summit, truncate infe- 

 riorly ; eye very large ; eye-spot close to the extremity of the 

 rostrum ; anterior antennae largely developed, dependent, strap- 

 formed, gradually widening from the base to the extremity; distal 

 half of anterior edge with a few notches ; extremity truncate, 

 with a piece as it were cut out of the posterior corner, to the 

 truncated portion of the apex are attached a number of long ten- 

 tacular seta?, and a little tuft of fine hairs occupies the notch just 

 described. Abdomen very deep, sweeping with a bold arch from 

 the origin of the two long geniculated setse to the terminal claws, 

 edge denticulate throughout, with a small bunch of fine hairs by 

 the vent ; claws very small. Length, -sVth of an inch. 



Found near London, by Dr. Baird ; at Belfast, by the late Mr. 

 W. Thompson ; at Eardingslake, and in the Glebe Engine Pond, 

 Sunderland, county of Durham ; in the East Lake, at Belsay, 

 Northumberland, and North Shaws Loch, Selkirkshire, by G. 

 S. B. Its range is known to extend in Europe from the neigh- 

 bourhood of Geneva in the south, to Norway and Sweden in the 

 north, and Russia in the east. 



2. Machotheix hiesijticoenis, n. sp. PI. XXIII, figs. 6, 7. 



Carapace in general form resembling the last, but broader, the 

 dorsal margin is smooth throughout (the serrulation of the edge, 

 which forms so marked a character in M. laticornis, being alto- 

 gether absent). The eye-spot is large and not so near the extre- 

 mity of the rostrum, but midway between it and the eye. The 



a 2 



