CYCLOPID^E AND CALANID^ OF MICHIGAN LAKES. 17 



In my paper on the Wisconsin Cyclopidce and Calaniclce ('93), agreeing 

 with Herrick and Brady, I expressed my belief that the two forms here 

 called fascus and albidus, the coronatus and tenuicomis of Clans, belonged 

 to the same species, fuscus being the more mature form. Since writing 

 that paper I have examined a large number of specimens from widely 

 separated localities, and I must acknowledge that I was wrong, and that, as 

 stated by Schmeil ('92), the two forms must be considered distinct, for I 

 have been utterly unable to find the connecting forms. The points of dif- 

 ference, as stated so elaborately by Schmeil, hold good for the American 

 specimens. C. fuscus has a sensory hair on the twelfth antennal segment, 

 the hyaline lamella of the 17th segment deeply notched, the third segment 

 of the antennule short, the inner borders of the furca thicklv beset with 

 hairs, and the egg sacs lie close to the abdomen, while C. albidus has a 

 clavate seta on the twelfth antennal segment, the membrane of the 17th 

 segment serrate or smooth, the inner borders of the furca either without 

 hairs or with only fine hairs, and the egg sacs lie separated from the abdo- 

 men. These characters, with the greater size of C. fuscus, serve to dis- 

 tinguish the species, while the less evident characters mentioned by 

 Schmeil are easily demonstrated. 



One characteristic not mentioned by Schmeil I have found constantly in 

 my specimens. The larger of the two terminal spines of the endopodite 

 of the fourth foot, instead of being serrated on its edges as is customary 

 in all the spines of the swimming feet, is beset on its inner margin with 

 long, rather irregular teeth, as shown in the plate. (Plate VI, fig. 7.) If 

 this peculiarity exists in the European forms, it would seem probable that 

 it would have been noted by some observer, but I have nowhere seen an 

 account of it. It may serve then to indicate a slight variation from the 

 European type. * 



I have found C. fuscus in the Michigan collections from only one 

 locality, Intermediate Lake. 1 have found it in several Wisconsin locali- 

 ties, though nowhere abundantly, and it is probable that it occurs in other 

 localities in Michigan. 



Cyclops albidus Jurine. 

 Plate VI, figs. 8-10. 



1820. Monoculus quadricornis albidus Jurine, pp. 44 and 47, pi. II, 



figs. 10 and 11; pi. Ill, fig. 24. 



1841. C. annulicornis Koch, H 21, pi. VI. 



1850. " quadricornis var. b Baird, p. 202, pi. XXIV, fig. 4. 



1857. " tenuicomis Claus, p. 31, pi. Ill, figs. 1-11. 



1857. " pennatus Claus, p. 35, pi. Ill, figs. 12-17. 



1863. " tenuicomis Claus, p. 99, pi. I, fig. 3; pi. II, fig. 17; pi. IV, 



fig. 5. 



1863. " tenuicomis Sars, p. 242. 



1863. " annulicornis Sars, p. 243. 



1863. " tenuicomis Lubbock, p. 202. 



1870. " tenuicomis Heller, p. 71. 



1872. " " Fric, p. 219, fig. 12. 



1874. " Clausii Poggenpol, p. 70, pi. XV, figs. 4-14. 



1875. " signatus Uljanin, p. 29, pi. IX, figs. 6-11; pi XI, fig. 8. 



1876. " " Hoek, p. 12, pi. I, figs. 1-4. 



