COPEPODS OF THE WOODS HOLE EEGION 149 



1-segmented, exopod ending in three stout spines, endopod in a 

 single acuminate point. Total length, 1.75-2 mm. 



Male. — Longer and narrower than the female; eyes closer together; 

 corners of fifth segment asymmetrical, the right one the longer and 

 reaching nearly the center of the second abdominal segment ; urosome 

 symmetrical; right fifth leg slightly longer than the left, hand of 

 chela on right leg swollen distally, thumb single, slender, sickle- 

 shaped, finger swollen in the center; endopod of left leg short, 1- 

 segmented, ending in a corrugated knob. Total length, 1.8-2.2 mm. 



Remarks. — This is evidently one of the most common copepods in 

 the area and is found mostly at the surface. Fish mentioned it as 

 one of the most common summer forms in Woods Hole Harbor, and 

 the specific name given it by Wheeler might seem to restrict it to that 

 season of the year, but Edwards found it abundant out in Vineyard 

 Sound in winter. The asymmetry of the lobes on the fifth segment 

 of the male and the fifth legs in both sexes are the most easily recog- 

 nized characters. 



Genus PONTELLA Dana, 1846 



Head with lateral hooks, but usually without a crest and separated 

 from the first segment ; one pair of dorsal cuticular lenses and a single 

 rostral lens in front of the ventral eye ; fifth segment separated from 

 the fourth, usually with pointed lobes at the corners, often asym- 

 metrical in the female; urosome 2- or 3-segmented in female and 

 asymmetrical, 4- or 5-segmented in the male and symmetrical; exo- 

 pods of first four pairs of legs 3-segmented, endopod of first leg 

 3-segmented, of second, third, and fourth legs 2-segmented; fifth 

 legs biramose in female, uniramose in male; right antenna of male 

 geniculate. 



KEY TO THE SPECIES 

 FEMALES 



1. Right posterior corner of fifth segment with a long curled and 



ragged streamer trailing backward far behind tips of caudal 



setae pennata (p. 150) 



No streamer, but pointed asymmetrical lobes on corners of fifth 

 segment . 2 



2. Left lobe on fifth segment acuminate and reaching to or beyond 



bases of caudal rami ; urosome 2-segmented 3 



Left lobe on fifth segment scarcely reaching distal margin of 



genital segment ; urosome 3-segmented 4 



3. Base of rostrum swollen into a large sphere ; right caudal ramus 



much enlarged ; genital segment with several outgrowths- securifer (p. 151) 

 Base of rostrum scarcely swollen at all ; right caudal ramus en- 

 larged but little; one outgrowth on genital segment spinipes (p. 152) 



4. Left lobe on fifth segment wider than long, the point turned out- 



ward ; exopod of fifth leg with a smooth inner margin meadii (p. 153) 



Left lobe on fifth segment longer than wide, the point turned 

 backward; fifth exopod with a large spine on inner 

 margin lobiancoi (p. 154) 



