Cyclops. 207 



extreme forms of serrulatus. So far as I know, however, no 

 one has reported forms intermediate between C. pulchellus and 

 C. navus. In my collections, while I have seen many instances 

 of considerable variation in C. pulchellus, particularly in the 

 form and armature of the furca, I have found no forms which 

 at all approach C. navus. Until such intermediate forms are 

 discovered, C. navus must be considered distinct. 



Cyclops pulchellus Koch. 



Plate IV. Figs. 18 and 19. 



1838. C. pulchellus Koch (3) H. 21, pi. 2. 



1857. " bicuspidatus Claus (8), p. 209, pi. XI, figs. 6 and 7. 



1863, " " << (9), p. 101. 



1863. " pulchellus Sars (11), p. 246. 



1870. " bicuspidatus Heller (12), p. 71. 



1872. " bicuspidatus Fric (13), p. 221, fig. 6. 



1876. " bicuspidatus Hoek (16), p. 17, pi. I, figs. 7-11. 



1880. " pulchellus Rehberg (19), p. 543. 



1880. " helgolandicus Rehberg (20), p. 64, pi. IV, fig. 5. 



1882. " thomasi Forbes (22), p. 649, pi. IX, figs. 10, 11 



and 16. 



1883. ,, pectinatus Herrick (25), p. 499, pi. VII, figs. 25-28. 



1883. " thomasi Cragin (24), p. 3, pi. Ill, figs. 1-13. 



1884. " thomasi Herrick (26), p. 151, pi. U, figs. 4, 5, 7 and 8. 



1885. " pulchellus Daday (27), p. 220. 



1886. " pulchellus Vosseler (28), p. 194, pi. V, figs. 19-28. 

 1891. " thomasi Forbes (35), p. 707, pi. II, fig. 8. 



1891. " bicuspidatus Brady (36), p. 13, pi. 5, figs. 1-5. 



1891. " thomasi Brady (36), p. 14, pi. VI, figs. 1-4. 



1891. " bicuspidatus Schmeil (37), p. 27. 



1891. " bicuspidatus Richard (39), p. 229, pi. VI, fig. 6. 



1892. " bicuspidatus Schmeil (41), p. 75, pi. II, figs. 1-3. 



1893. " thomasi Fcrbes (42), p. 249, pi. XXXIX, figs. 9-12; 

 pi. XL, fig. 13. 



Herrick considered C. thomasi a variety of C. pulchellus Koch. 

 Brady also raises the question as to the specific distinction of 

 the American form. I have gone over the literature of the sub- 

 ject with considerable care, and I can see no good reason for 



