BYRNES: CYCLOPS OF FRESH WATER. 9 



constant; the typical number of hairs on each segment is indicated 

 by the following series of figures, counting from the base: 8, 4, 2. 6, 

 4, 2, 2, I, I, o, I, ?, o, I, 2, 2. 8. 



The armature of the twelfth segment shows a tendency to vary; 

 occasionally but one distal hair is present; again two are present, 

 in which case one is larger than the other. 



Cyclops Sigiiatus, var. Coronatus^ (Plates II., III.). — This form 

 (also known as Cyclops fusiics, Jurine) has a short second 

 joint in the antennule, PI. II., Fig. 3, serrations in the hyaline piate 

 on the two distal segments of the antennae (Fig. 4), a short, almost 

 square, basal segment in the fifth foot (Fig. 5), and numerous hairs 

 on the inner margins of the caudal stylets (Fig. 6). The notches 

 in the hyaline plate of the antennae form gradually and may or may 

 not be present. In Fig. 4, they are seen on the last segment only. 



The adult armature of the terminal segments of the swimming 

 feet is as follows; 



Foot No 



Ramus, Outer or Inner . . 



Outer Spines 



Apical Spines 



Apical Seta 



Inner Setse 



II 



I 



l(sa) 

 1 

 1 

 3 



I 



l(sa) 



1 



1 



3 . 



Ill 



I 



1 (saj 

 1 

 1 

 3 



\\ 



I 



l(sa) 



1 



1 



sa=seta in place of spine. 



The older forms of coroiiafits are usually densely pigmented, 

 brown and blue tones prevailing. They often become very coarsely 

 serrated and hairy. The ova are dark and the ovisacs are carried 

 closely pressed to the abdomen. 



Few striking variations have been observed in these forms. They 



* I have used the more recent name, C. si^iiatits, variety coroiiatits, instead 

 of the older name, C. fuscus. Jurini:, because it expresses more clearly the 

 evidently close relationship that exists between C. sigiiatus, variety coronatus, 

 and the allied form, C. sigiiatus, variety annulicoruis, called C. albtdus by 

 Jurine. 



