Mamli — North American Species of Diaptomus. 483 



long as wide, convex on both inner and outer margins, and 

 with the inner margin setose. The second segment is slightly 

 longer than the first, and armed with two setose pads on its 

 inner margin. It terminates in a blunt digitiform process, 

 and from the inner margin projects an acuminate, curved 

 spine. Tlie endopodite is slender, indistinctly two-segmented, 

 reaches about one-half the length of the second segment of the 

 exopodite, and is setose at tip. 



Length of female, 4 mm. Length of male, 3.5 mm. 



The original description was from material found in Fresno, 

 California. It was later reported by Brewer from Lincoln, 

 ISTebraska. These are thus far the only localities for the 

 species, but doubtless it will l)e found at intermediate points. 



The description, as given above, is largely a compilation 

 from DeGuerne and Richard and Brewer, with such modifica- 

 cations as a very limited personal acquaintance with the 

 species has permitted. 



In the plate, the figures of the antenna and female fifth 

 foot are from DeGuerne and Kichard, the male fifth foot from 

 a preparation kindly loaned by Professor H. B. Ward. 



DIAPTOMUS NovAMExicAisrus Herrick. 



Plate XXVI, figs. 0, 10. 



1895. Diaptomus novamexicanus Ilerrick, p. 4G, figs. 27-29. 

 1895. Diaptomus novamexicanus Ilerrick and Tunier, p. TO; 



pi VI, figs. 7-10. 

 1897. Diaptomus novamexicanus Schacht, p. 149. 



"A small species of robust form. Cephalothorax widest in 

 front of the middle. The first segment equals in length the 

 rest of the cephalothorax. The last segment is armed on each 

 side with a minute spine. 



'The first abdominal segment of the female exceeds in length 

 the rest of the abdomen. It is dilated laterally, and armed on 

 each side with a small spine. The second segment is very 

 short. The furcal rami equal in length the preceding segment. 

 The furcal setae are short. 



