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Cincinnati Society of Natural History. 



Outer ramus. Inner ramus. 



First foot ex. 3 spines 1 seta. 



ap. 2 setae 1 spine, 1 seta. 



in. 3 setae 3 setae. 



Second and ex. 3 spines 1 seta. 



Third feet.... ap. 1 spine, 1 seta 2 setae. 



in. 4 setae 3 setae. 



Fourth foot... ex. 2 spines 1 seta. 



ap. 1 spine,. 1 seta 2 setae. 



in. 4 setae 2 setae. 



This differs from the armature, as given by Herrick, in 

 having, instead of two setae apieally on the inner ramus of 

 the first foot, a spine and seta. In the same place on the 

 fourth foot I have found two setae instead of a spine and seta. 



This species is very abundant where it is found, but I have 

 found it only three times near Lincoln. Near Grinnell, 

 Iowa, it is one of the most abundant forms. It is said to be 

 pelagic. 



Canthocamptus minutus Mueller. 



Antennae eight-jointed, the first four bearing numerous 

 setae. The antennae about equal in length to the first thoracic 

 segment. The first segment is marked by a depressed area 

 dorsal and median said to be sensory. The remaining seg- 

 ments of the thorax decrease in length, and are much shorter 

 than the abdominal segments. The whole surface of the body, 

 but more especially of the abdomen, is ornamented with fine 

 teeth. On the abdomen the most conspicuous are a lateral 

 row on the posterior margin of each segment. 



The abdomen is not separated from the thorax by any deep 

 constriction and the first abdominal segments are broader 

 than the last thoracic. The furcae are small and about two 

 and one-half times as long as their greatest breadth. Each 

 bears one terminal seta more than twice the length of the 

 second, and several shorter ones. 



Both rami of all the swimming feet are three-jointed. 



The fifth foot is two-jointed. The first joint is twice as 

 broad as long, and bears five strong plumose seise and one 

 very small one on the inner side of the second joint and one 



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