SENECELLA CALANOIDES, A EECENTLY DESCRIBED 

 FRESH-WATER COPEPOD 



By Chancey Judat 

 Biologist of the Wisconsin Geological and Natural History Survey 



During the summers of 1910 and 1918 limnological studies of 

 the Finger Lakes of New York were made for the United States 

 Bureau of Fisheries. Plankton catches were obtained from the va- 

 rious lakes that were Adsited, and a recent taxonomic study of the. 

 copepods in this material led to the discovery of an interesting cala- 

 noid form which represented not only a new species but also a new 

 genus of fresh- water Copepoda. This copepod was found in catches 

 obtained from the lower water of 3 of the 10 lakes that were studied, 

 namely, Seneca, Cayuga, and Owasco. It was briefly characterized 

 in Science.^ 



Genus SENECELLA Juday 



Senecella Juday, Science (n. s.), vol. 58, 1923, p. 205. 



Generic characters of tnale and female. — The cephalothorax is 

 nearly three times as long as its maximum width, evenly and grad- 

 ually vaulted anteriorly, without a rostrum or rostral filaments at 

 the anterior end. The head is only indistinctly separated from the 

 first thoracic segment. In the female the first thoracic segment is 

 strongly carinated on its ventral surface. The abdomen is sym- 

 metrical, consisting of four segments in the female and five in the 

 male, the fifth segment in the latter being very short. The caudal 

 rami in both sexes are rather short; each ramus bears five terminal 

 setae and a small seta on the upper surface near the middle of the 

 inner edge, ciliated on the inner margin. 



The first antennae are longer than the cephalothorax, with 25 

 segments. The right antenna is exactly like the left in the adult 

 male. Each antenna bears 15 sensory appendages in the adult male, 

 but only 7 in the female. The eighth and ninth segments are more 



1 New Series, vol. 58, 1923, p. 205. 



No. 2541. -Proceedings U. S. National Museum. Vol. 66, Art. 4 



9112—25 



