388 HEY. A. M. NOXiilAN AND ME. G. S. BEADY 



1848. Lynceus truncatus, Lievin. Die Branchiopoden der Dan- 

 ziger Gegend, p. 40. PI. X, figs. 2, 3. 



1850. Peracantha iruncata, Baird. Brit. Entom., p. 136. PI. 



XVI, fig. 1. 



1851. Lynceus truncatus, Fischer. Mem. presentes a 1' Acad. 



Imp. des Sciences de St. Petersbourg par divers Savans, 

 Vol. VI, p. 190. PI. IX, figs. 7-11. 



1853. Lynceus truncatus, Lilljeborg. De Crust. Clad. Ostra. et 

 Copep., p. 82. PI. VI, fig. 10. 



1860. Lynceus truncatus, Leydig. Naturgeschiehte der Daph- 

 niden, p. 224. 



1863. Peracantha truncata, Schoedler. Neue Beitrage der 

 Naturgescb.icb.te der Cladoceren, p. 40. PI. II, figs. 

 29, 30. 



Carapace ovate, often dorsally gibbous, posteriorly subtrun- 

 cate ; ventral margin somewhat flexuous and arcuate, anteriorly 

 furnished with a row of spiny processes which have their apices 

 curved upwards, posteriorly strongly ciliated ; posterior extremity 

 armed all along the edge with a series of large tooth-like pro- 

 cesses, the hindermost of which are directed backwards ; surface 

 divergently striated. Head terminating in an acute rostrum, 

 projected horizontally, and not extending beyond the ventral line 

 of the carapace ; anterior antenna? very short, thick, appearing 

 beneath the rostrum ; posterior antennae short. Eye of moderate 

 size ; eye-spot scarcely half as large as the eye, situated nearer to 

 it than to the extremity of the rostrum. Abdomen of moderate 

 length and size, rather broad, wider at the base than at tbe ex- 

 tremity, distally truncate, the angle pronounced and somewhat 

 produced ; superior margin bearing about twelve spines ; claws 

 of moderate length, slightly curved, furnished with two second- 

 ary spines springing from near the base, and .situated close to- 

 gether. Length, - 3 Vth of an inch. 



Common in ponds, slow-running streams, and lakes; ranging 

 throughout the whole of northern Europe. 



Schoedler describes a closely allied form under the name of 



