42 COLD SPRING HARBOR MONOGRAPHS. VH. 



Fig. 5. A mature Cyclops from Cypress Hills, L. I., showing the general 

 proportions of the body. The antenn?e contain thirteen segments. The rami 

 are three-jointed with the armature of C. parens. Although the antennae are 

 immature, the form is sexually developed, as is indicated by the enlarged 

 first abdominal segment and the condition of the receptaculum seminis. 



Fig. 6. The rudimentary fifth foot of Fig. 5. 



Fig. 7. The receptaculum seminis of Fig. 5. 



PLATE XI. CYCLOPS PARCUS. Herrick. Young Form 

 Camera Drawings. Leitz. 



Fig. I. The outline of a young Cyclops, showing the general proportions 

 of the body. Immaturity is indicated by the small number of segments in 

 the antenna; ; by the presence of two segments instead of three in the rami 

 of the swimming feet ; and by the uniform size of the abdominal segments. 



Fig. 2. The right outer and inner rami of the fourth pair of swimming 

 feet of Fig. i, showing two segments. The distal segment is beginning to 

 break into two, the second and third of the adult condition. The position of 

 the setse and spines with relation to the adult condition is determined before 

 the segments are actually formed. The seta on the outer margin of the inner 

 ramus of the fourth foot and the two spines on the outer margin of the outer 

 ramus, indicate that the form is C. parens (Herrick). 



Fig. 3. The rudimentary fifth foot of Fig. i. 



CYCLOPS MODESTUS. 



Fig. 4. An outline of an adult female, showing the general proportions 

 of the body, the antenna; and the caudal stylets. 



Fig. 5. The ventral view of the fifth thoracic segment with the rudimentary 

 fifth feet. The fifth feet are clearly three-jointed and the first abdominal 

 segment is greatly elongated. 



PLATE XII. CYCLOPS SERRULATUS. 

 Camera Drawings. Leitz. 



Fig. I. An adult female, showing the general proportions of the body. 



Fig. 2. A side view of an adult female, showing the general proportions of 

 the body. 



Fig. 3. The first pair of swimming feet of Fig. i. They are dispropor- 

 tionately small. 



Fig. 4. The fourth pair of swimming feet of Fig. I, drawn for comparison 



with Fig. 3. 



Fig. 5. The rudimentary fifth foot of Fig. r. 



