50 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 82 



first segment of the exopod is about twice as long as broad and has 

 a small spine on its outer margin at about three-fourths of its length. 

 The second segment of the exopod is one-third as long as the first; 

 it has a small curved spine near the distal end ; this spine is turned 

 inward across the segment. A narrow hyaline lamella extends along 

 the inner side of the second segment and the base of the hook. The 

 terminal hook is slender, recurved at the tip, and nearlj^ as long as 

 the whole right foot. 



The second basal segment of the left foot (pi. 24, fig. 4) is twice 

 as long as broad. The endopod is a triangular plate with sides 

 about as long as the first segment of the exopod; the outer distal 

 angle is drawn out in a slender, pointed process about as long as the 

 sides of the endopod. The second segment of the exopod has a 

 convex outer margin and a concave inner ; there is a protuberance at 

 the inner proximal angle and a small digitiform process and a spine 

 at the termination. 



Length, 2.45 mm to 2.55 mm. 



Occurrence. — This species was first described from collections from 

 Seneca, Cayuga, and Owasco Lakes, N. Y. It has also been found 

 in Lake Timagami and Lake Nipigon in Canada. In 1894 the 

 author found immature specimens of an unnamed copepod in Pine 

 Lake, Mich. In 1898 he received from A. J. Woolman similar mate- 

 rial collected in Lake Superior. It is now evident that both of these 

 collections were of Senecella calanoides. It is characteristic of deep 

 water and may eventually be found to have a wide distribution. 



Remarks. — Juday correctly assigned this form to a new genus. 

 It seems clear too that it must be placed in a new family, as it does 

 not correspond to any recognized family. Therefore, the family 

 name Senecellidae is here introduced for this interesting form. 



