68 
BULLETIN OF THE LABORATORIES 
Althoiigli not abundant, this species has been encountered several 
times. 
Sp. 7. AlOflCb ^lacialis, Birge. 
Alona glacialis, C. L. Herrick, Final Report on Minn. 
Crustacea, p. lOo. 
This species is very scarce. 
J^p- 8. Alona intermedia, bars. 
Alona intermedia, * C. L. Herrick, Final Report on 
Minn. Crustacea, p. loi; pi. I, fig. 15. 
Sub-genus Pleura xus. 
Sp. 9- Pleurojoas denticulatus, Birge. 
Pleur oxus denticulatus, C. L. Herrick, Final Report 
on Minn. Crustacea, p. no; pi. G, figs. 12, 13. 
This species is abundant in all of our canal basins and in several 
of the larger ponds. 
The number of teeth upon the caudo-ventrad angle of the shell 
varies from one to three. 
Sp. 10. Pleurojoas hamatus, Birge. 
Pleuroxus hamatus, " C. L. Herrick, Final Report on 
Minn. Crustacea, p. no; pi. H, fig. i. 
Although not widely distributed, this species is quite abundant in 
the few canal basins and large ponds where it does occur. 
A few slight deviations from the descriptions that I have seen of 
this species tempt me to give a complete description. I have not seen 
Professor Birge’s description. Shell long and low, about twice as long 
as high. Length about 478 micro-millimetres, height about 278 
micro-millimetres- Caudad margin of shell straight, about two- 
thirds as high as the greatest height of the shell. Caudo- 
ventrad angle of shell not toothed, but is margined with min- 
ute sharp points. Ventrad margin straight or feebly concave, 
supplied with a fringe of long hairs. Beak curved caudad, about 
twice as long as the antennules, including hairs. Shell is coarsely 
marked with the same lines that adorn the shell of P. denticulatus. 
In addition, the whole shell is closely striated with fine, undulating, 
sub-parallel, longitudinal, lines. These striations extend out upon the 
beak. Eye larger that the pigment fleck. First foot of the female 
supplied with a claw. The post abdomen is long, slender, truncated. 
