62 PROCEEDINGS OF THE ACADEMY OF [Jan.^ 



Fig. 2. — C. albidus, adult female, showing the characteristic divaricate- 

 position of the egg-sacs. Oc. 1, obj. 1 (Bausch & Lomb). 

 Fig. 3. — Dorsal aspect of stylets and last abdominal segment of C. fuscuii. 



Oc. 3, obj. 3. , * 



Fig. 4. — Stylets and last abdominal segment of C. albidus. Oc. 1, obj. 3 



(B. & L.). 

 Fig. 5. — Three proximal joints of the second female antenna, C. fuscua. 



Oc. 2, obj. 3. 

 Fig. 6. — Third and fourth joints of the second female antenna, C. albidua. 



Oc. 1, obj. 3 (B. & L.). 

 Fig. 7. — Terminal segment of first female antenna, C. fuscus, showing the 



typical deep serrations of the hyaline plate. Oc. 2, obj. 3. 

 Fig. 8. — Terminal segment of first female antenna, C. albidus. The finely 



serrated plate is characteristic. Oc. 3, obj. 5. 

 Fig. 9. — Twelfth segment of the first female antenna of C. fuscus, showing 



the armature of minute serrations and the sense-hair. Oc. 2, obj. 5. 

 Fig. 10. — Twelfth segment of the first antenna of a female C. albidus, showing 



rows of "thorns" and sense-club. Oc. 2, obj. 5. 

 Fig. 11. — Receptaculwm seminis of C. fuscus. Oc. 3, obj. 3. 

 Fig. 12. — Receptaculum seminis of C. albidus. Oc. 3, obj. 3. 

 Fig. 13.— Fifth foot of C. albidus. Oc. 2, obj. 5. - 



Fig. 14. — Distal segment of the inner ramus of the fourth pair of swimming 



feet of C. albidus, showing a group of small hairs in place of the second seta 



of the inner side. Oc. 0, obj. 5. 



Plate II. — Figs. 1-5, Cyclops bicuspidatus Claus. Figs. 6-11 Cyclops modestus,. 



Herrick. 

 Fig. 1. — An adult female (slightly extended by pressure). Oc. 0, obj. 3. 

 Fig. 2. — Lateral view of a stylet showing the minute serrations near the- 



anterior end. Oc. 3, obj. 5. 

 Fig. 3. — The sense-club of the twelfth segment of the first female antenna^. 



Oc. 3, obj. 7. 

 Fig. 4. — A foot of the fifth pair. Oc. 3, obj. 7. 

 Fig. 5. — The receptaculum seminis. Oc. 3, obj. 3. 

 Fig. 6. — An adult female. Oc. 0, obj. 3. 

 Fig. 7. — An adult male with first antennae folded under the cephalothorax. 



Oc. 0, obj. 3. 

 Fig. 8. — Stylets and last abdominal segment. Oc. 2, obj. 5. 

 Fig. 9.— A foot of the fifth pair. Oc. 1 (B. & L.), obj. 7. 

 Fig. 10. — Lamella of the third pair of swimming feet. Oc. 1 (B. & L.),. 



obj. 5. ■ 



Fig. 11. — The three terminal joints of the first female antennae showing 



hyaline plates and sense-hair. Oc. 1 (B. & L.), obj. 5. 



Plate III. — Figs. 1-5, Cyclops prasinus Fischer. Figs. 6-11, Cyclops varicans: 



Sars. 

 Fig. 1. — An adult female. Oc. 2, obj. 3. 



Fig. 2. — The stylets and last abdominal segment. Oc. 3, obj. 5. 

 Fig. 3. — The three terminal joints of the female first antenna showing the 



characteristic hyaline plates. Oc. 2, obj. 7. 

 Fig. 4.— The fifth foot. Oc. 2, obj. 7. 

 Fig. 5. — The receplaculum seminis. Oc. 3, obj. 5. 

 Fig. 6. — A mature female of C. varicans with eleven-jointed first antenna? :; 



a winter transitional form. Oc. 2, obj. 3. 

 Fig. 7. — The stylets and last abdominal segment. Oc. 2, obj. 5. 

 Fig. 8. — An eleven-jointed antenna of the first pair in the female. Oc. 3,. 



obj. 5. 

 Fig. 9. — The fifth thoracic segment showing the rudimentary fifth feet.. 



Oc. .3, obj. 5. 

 Fig. 10. — The receptaculum seminis. Oc. 0, obj. 5. 

 Fig. 11. — A two-jointed swimming foot of the third pair. The division 



of the third joint is always inilicated by minute rows of hairs. Oc. 2, 



obi. 5. 



