CYCLOPOIDEA. 



1125 



base, as shown in figure 6 a, Plate 82, representing P. valida, and the 

 beak admits usually of slight motion at this suture. In some species, 

 the beak is very much in flexed, and in others it is directed downward 

 simply; in the latter, the front in an upper view is more or less 

 pointed or triangular. 



Eyes. — The superior eyes have each a distinct spherical lens ; the 

 pigment is either blue-black or carmine-black. The pigment of the 

 inferior eyes forms a circular or elliptical or reniform spot, behind or 

 between the superior eyes, as seen in an upper view through the head. 

 Sometimes it is so beneath the superior eyes as hardly to be distin- 

 guished in this view. The existence of this pigment seems to show 

 that these are true eyes ; yet, we cannot but recall the dark " eye- 

 spot" in the front of a Daphnia, which has been shown by Schodler to 

 contain otolites, and therefore to be the ear of the animal.* 



In the Calanoid species, resembling Calanus in the transverse posi- 

 tion of the anterior antennae and the three terminal setae of the smaller 

 branch of the posterior antennae, the inferior eyes are very small. 



Anterior antennae. — The anterior antennae vary in the number of 

 joints from nine to twenty-four, which last is probably the normal 

 number. The setae are arranged along the front margin, as in the 

 Calani. 



The first joint has usually a very short seta or two at apex. On 

 the second there are a few quite short setae on the front margin, and 

 generally one or more longer at apex, varying from a length of one 

 diameter of the joint to three diameters, seldom four. Beyond the 

 second, for some distance, the seta3 are often crowded (the joints being 

 short), and they are a little longer than those along the middle of the 

 antenna. There is sometimes a minute fringe on the posterior side of 

 the antenna, extending from the second joint through half the length 

 of the organ. 



The right male antenna has a geniculating joint at the fifth or sixth 

 articulation from the apex, as described in our general remarks on the 

 Calanidae, and illustrated on Plate 70, figs. 26 to 36. 



In a few species resembling the Calani, the right antenna scarcely 

 differs from the left, except in the geniculating articulation itself, and 

 a very slight enlargement along the middle portion. 



* Archiv fur Naturgeschichte, 1846, p. 301. 



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