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 

 Jias three blunt spines upon its apex and is armed with minute 

 bristles within. Th3 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 ail 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 (Lilljeoorg) 



(32) p. 50, pi. I, figs. 5, 6 and 14, pi. Ill, fig. 25. 

 1891. Dicqitomus 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. 

 Clair river, and one Jake in northern Wisconsin. It was de- 

 scribed by Lilljeborg from specimens obtained in Greenland 

 .and Newfoundland. It was later reported from Iceland (39). 



