CYCLOPIAS AND CALANID^E OP MICHIGAN LAKES. 7 



FAMILY CALANID^E.— Genus DIAPTOMUS Westwood. 

 KEY TO SPECIES OF DIAPTOMUS FROM CHARACTERISTICS OF THE MALE. 



Antepenultimate joint of antenna without appendage, 



Fifth feet nearly equal in length, . oregonensis. 



Left fifth foot shorter than right, 



Inner ramus of left fifth foot about equal in length to 

 first joint of outer ramus, terminal hook of right foot 



not markedly angular, pallidus. 



Inner ramus of left fifth foot about twice as long as 

 first joint of outer ramus, terminal hook of right foot 

 with an abrupt angle at about midway of its length, Beighardi. 



Antepenultimate joint of antenna with hyaline lamella, leptopus. 



Antepenultimate joint of antenna with appendage, # 



Appendage short and blunt, 



Left fifth foot hardly reaching end of basal joint of 

 right, lateral spine of terminal joint of right foot 

 weak, reaching about to end of joint, species large, 



occurring only in spring, sanguineus. 



Left fifth foot reaching to about one-third the length 

 of the terminal joint of the right, lateral spine of 

 terminal joint large, reaching to nearly one -half the 



leifgth of the terminal hook, Birgei. 



Appendage as long or longer than the penultimate joint, 

 Terminal hook of right fifth foot broad, lateral spine 



minute,,. minutus. 



Terminal hook falciform, 



Lateral spine nearer outer extremity of joint, sicilis. 



Lateral spine stout, nearer base of joint, Ashlandi. 



Diaptomus sicilis Forbes. 

 Plate VII, figs. 1 and 11. 



1882. D. sicilis Forbes, p. 645, pi. VIII, figs. 9 and 20. 



1884. " " Herrick, p. 142, pi. Q, fig. 18. 



1889. " " DeGuerne and Kichard, p. 23, figs. 13 and 14, pi. II, 



fig. 13. 

 1891. " " Forbes, p. 702, pi. 1, fig. 6. 

 1893. " " Marsh, p. 197, pi. Ill, figs. 8 and 10. 



D. sicilis is found everywhere in the Great Lakes, in Lake St. Clair and 

 in the Detroit River. It is also found in Pine Lake, and very likely occurs 

 in other bodies of water having direct connection with the Great Lakes. 



I do not know of its occurrence in bodies of water away from the 

 Great Lakes, except in Green Lake (Marsh '91 and '93), and Lake Geneva 

 (Forbes, '90), and both of these are deep-water lakes. 



Diaptomus Ashlandi Marsh. 

 Plate VII, fig. 2. 



1893. D. Ashlandi Marsh, p. 198, pi. Ill, figs. 11-13. 

 When I described this species in my paper on the Cyclopidai and 

 Calanidce of Wisconsin, I knew of only two localities for it, Lake Supe- 



