26 



SPECIES I. 



Plate I. Fig. 18. 



Crepidocercus Setig-er. sp. nov. 



Length, 0.4-0.5 mm. Height, 0.27-0.32 mm. 



Measurements from one specimen. 



Length, 0.37 mm. Height, 0.25 mm. Length of hind margin, 

 0.12 mm. Length of spine of ventral margin, 0.017 mm. Length 

 of sefce of ventral margin, 0.02-0.04 mm. Diameter of eye, 

 0.028 mm. Diameter of macula nigra, 0.01. Length of anten- 

 nule, 0.041 mm. Length of post-abdomen from " heel " to "toe," 

 0.11 mm. Length of terminal claw, 0.016 mm. This specimen 

 was rather below the average in size. 



The color is yellow, rather opaque. The specific name is taken 

 from the setse with which the post-abdomen is armed. Mad- 

 ison, Wis. Bare. Male not seen. 



This species is to some degree intermediate between Alona and 

 Pleuroxus. It resembles the first in the size of the rostrum and 

 the single basal spine of the terminal claws. In general shape 

 and markings it recalls Pleuroxus. Graptoleberis is the only 

 form whose post-abdomen at all resembles that of Crepidocercus. 

 The mode of motion is quite peculiar. 



GENUS 4. 

 Graptoleberis. Sars, 1867. 



Gkaptolebeeis. Kurz. 



Alona, e. p. Baird, Schodler, P. E. Miiller. 



Ltnceus, e. p. Leydig, Liljeborg, Fischer et al. 



8PECIES 1. 

 Plate I. Fig. 17. 



Graptoleberis Inermis. sp. nov. 



Length, 0.6-0.8 mm. Height, 0.30-0.35 mm. 



There is no indentation at the junction of head and thorax, but 

 the dorsal margin rounds regularly over from the point of the 



