15 



tween the valves and bent inward toward the median line, so that 

 the ends of the two hooks are almost in contact when at rest. 

 The ends are covered with fine teeth. The post abdomen has the 

 same general shape as that of the female. The hairs on it are 

 finer, hardly perceptible. There are no terminal claws, and the 

 post- abdomen is prolonged into an elevation about 0.05 mm. 

 long, on whose summit the vas deferens opens. 



Madison, Wis., 1877. Not rare in shallow and weedy water. 



Sub-family 3. Bosminime. 



GENUS 1. 



Bosmina. Baird, 1850. 



SPECIES 1. 



Bosmina Longikostris. O. F. Miiller. 



Lynceus longirostris, O. F. Miiller. Entomostraca, p. 76, Tab. X, figs. 7-8. 

 Bosmina " Sars, 1. c, p. 153. 



" " Schodler. Cladoceren des frischeii Haffs. p. 45, figs. 



16-17. 

 P. E. Miiller. 1. c, p. 146, Tab. Ill, figs. 8-9. 

 " " Kurz. 1. c, p. 29. 



Length, circ. 0.39 mm. 



These specimens agree with Bosmina longirostris in all respects 

 except size, which is considerably greater in our form. 



Cambridge and Southampton, Mass.; Madison, Wis. Bather 

 rare. 



SPECIES 2. 



Bosmina Cornuta. Jurine. 

 Plate JJT Fig. 10. 



Monoctjlus cornutus, Jurine. 1. c, p. 142, Tab. 14, figs. 8-10. 

 Eunica longirostris, Koch. 1. c, H. 35, Tab. XXIII. 

 Bosmina cornuta, Sars. 1. c., p. 280. 



Schodler. Clad. fr. Haffs. p. 49, Tab. Ill, figs. 18-22. 



P. E. Miiller, 1. c., p. 147. 



Specimens belonging to this species were found at Easthamp- 

 ton, Mass., Aug., 1878. Length, 0.3 mm. 



& 



