ON BOSMINIDiE, MACBOTHMCTDJE, ETC. 387 



Lynceus acanthocercoides has been found in Russia, Prussia, and 

 Norway. 



12. Ltncetjs falcatus, (G. 0. Sars). PI. XYIII, fig. 4 ; and 

 PI. XX, fig. 1. 



1861. Alona falcata, G. 0. Sars. Om de i Omegnen af Christ. 



forekom. Cladocera, p. 20. 



1862. Harporhynchus falcatus, Sars. Om de i Omeg. af Christ. 



forekom. Clad. Andet. Bidrag., p. 41 . 



Carapace of remarkable form, deeper behind the middle than 

 in front ; dorsal margin slightly arcuate ; ventral nearly straight, 

 fringed with long cilia ; posterior obliquely and widely truncate ; 

 infero-posteal angle rounded off, without spines ; surface ob- 

 scurely striated. Head very erect at first, produced subse- 

 quently into a very long slender falciform rostrum, which is 

 curved downwards between the posterior antennae ; anterior an- 

 tennas large; posterior short. Eye-spot much larger than the 

 eye. Abdomen having no marginal teeth, except two or three 

 of considerable size at the posterior angle, which is well rounded 

 off; the sides, however, of the abdomen, are furnished with 

 several rows of delicate hair-like spines ; claws long and nearly 

 straight, with a secondary spine of moderate length springing 

 from the base. Length, -§Vth of an inch. 



Sars describes the male as having the long rostrum larger than 

 in the female, widening and swollen at the extremity, and ap- 

 parently movable, so much so that he suggests that it may be 

 used for the purpose of seizing the female. 



Sars is the only writer who has described this interesting spe- 

 cies. In this country we have met with it in two of the lakes of 

 Northumberland, viz., Sweethope (G. S. B.) and Green Lee (A. 

 M. N.) ; also in Lochend Loch, Kirkcudbrightshire ; and Loch- 

 maben Castle Loch, Dumfriesshire (G. S. B.). In all these 

 localities it was numerically scarce. 



13. Lynceus teuncatus, Midler. PL XXI, fig. 9. 



1781. Lynceus truncatas, Miiller. Entomostraca, p. 75. Pi. 

 XI, figs. 4-6. 



