Diaptomus. 
199 
lateral spine is stout, curved, situated near the inner end. 
The terminal hook is slender and falciform. The inner ramus 
is slender, one-jointed, and about one-third longer than the 
first joint of the outer ramus. 
The left foot extends a little beyond the first joint of the 
outer ramus of the right. The second joint of the outer ramus 
has three blunt spines upon its apex and is armed with minute 
bristles within. The inner ramus is slender, one-jointed, and 
reaches about half the length of the second joint of the outer 
ramus. 
Length of male, .89 mm. ; female, .97 mm. 
Localities, Lake Superior and Lake Erie. 
D. ashlandi is smaller than D. sicilis , from which it is dis¬ 
tinguished by the form of the male fifth feet. The appendage 
of the antepenultimate joint of the right male antenna resem¬ 
bles the form in sicilis and minutus. The female is not so 
readily distinguished, although the fifth feet are more slender 
than in sicilis. 
I have specimens from only two localities. In pelagic col¬ 
lections made by Prof. Birge at Ashland it occurred with D. 
■oregonensis and D. minutus. In a collection made by Miss 
Merrill on Lake Erie nearly all the Diaptomi belonged to this 
species, D. sicilis being represented very sparingly. 
Diaptomus minutus Lilljeborg. 
Plate IV. Figs. 1-3. 
1889. Diaptomus minutus DeGuerne and Richard (Lilljeborg) 
(32) p. 50, pi. I, figs. 5, 6 and 14, pi. Ill, fig. 25. 
1891. Diaptomus minutus Marsh (38) p. 212. 
I reported D. minutus in 1891 from Green Lake. I have 
since found it in collections from the Great Lakes, the St. 
€lair river, and one iake in northern Wisconsin. It was de¬ 
scribed by Lilljeborg from specimens obtained in Greenland 
and Newfoundland. It was later reported from Iceland (39). 
