122 



Cincinnati Society of Natural History. 



b. The first joint of the outer ramus bearing a pro- 

 jection on its inner side beyond the inner ramus. 



siciloides. 



2. The inner ramus of the left fifth foot not so long as the 

 first joint of the outer ramus. saltillinus n. sp. 



C. The antepenultimate joint of the male right a?itenna bear- 

 ing a hook longer than the following segment. eiseni. 



Diaptomus pallidus Herrick. 



A rather small species, measuring scarcely a millimeter in 

 length. It is broadest at its third segment. 



The first segment is two-fifths of the cephalo-thorax, the 

 other segments being nearly equal. The last bears two 

 minute teeth. The first abdominal segment of the female is 

 a little longer than the two remaining segments and dilated 

 anteriorly. The last is a little longer than the second, and 

 split for half its length. The furcse are ciliated on their inner 

 aspect, and are slightly longer than broad. 



The antennae reach to the end of the furcal setse. 



The basal joint of the fifth foot of the female is triangular. 

 The inner margin of inner ramus bears several small hairs, 

 and at the inner side of the tip are two curved spines, one 

 about twice the length of the other. The first joint of the 

 outer' ramus is not quite as long as the inner ramus. The 

 claw is well curved, and is much narrowed beyond the point 

 where the spines arise on the outer aspect. 



The antepenultimate joint of the right male antenna bears 

 no armature of any kind. It is not much swollen proximally 

 to the geniculating joint. 



The right fifth foot of the male is long and slender. The 

 inner ramus is a little longer than the first joint of the outer 

 ramus. The terminal joint is elongated, and bears a slight 

 notch at its second third on the inner aspect. The slightly 

 curved claw is nearly regular. It is marked by very fine 

 teeth. The accessory spine is close to the claw, is small and 

 curved inward. 



The basal joint, inner ramus, and the first joint of the outer 

 ramus of the left foot are nearly the same in length as the cor- 

 responding parts of the right foot. The terminal joint bears 



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