148 Illinois State Laboratory of Natural History. 



armed on the outer margin, a short distance above the apical 

 angle, with a spine-like hair. First segment of outer ramus 

 subquadrate, slightly narrower than the second basal seg- 

 ment, and about as wide as long ; second segment about as 

 wide as the first and twice as long, provided at the end of 

 the proximal third with a small bead-like tubercle. Mar- 

 ginal spine very large and strong, longer than the segment 

 itself, somewhat sinuously curved, and inserted near the 

 distal angle. Terminal hook very long, as long as the remain- 

 der of the right leg including the basal segments, but not 

 twice as long as the marginal spine ; very slightly recurved 

 at the tip and denticulate at the inner margin. 



Inner ramus of the right fifth leg one-segmented, very 

 short, barely reaching the end of the first segment of the 

 outer ramus ; apex bluntly rounded and delicately hairy. 



First segment of outer ramus of fifth foot of female (PI. 

 XXVII., Fig. 2) subquadrate, about twice as long as wide. 

 Second segment, or unguiform process, about as long as the 

 first, subcorneal or but slightly curved, delicately denticulate 

 on the inner margin. Third segment small but distinct, armed 

 with two spines, the inner of which is more than twice as 

 long as the outer, reaching about to the middle of the second 

 segment. 



Inner ramus of fifth foot of female indistinctly two-seg- 

 mented, short, reaching just beyond the end of the first seg- 

 ment of the outer ramus ; apex bluntly triangular, armed 

 with a few short hairs, the innermost of which is longer than 

 the rest and spine-like. 



Length of female 1.2 mm. ; of male 1.05 mm. 



The material in Avhich the specimens described were found 

 was loaned me by Mr. Adolph Hempel, of Gotha, Florida, 

 and was collected by him in a series of Florida lakes from 

 January to March, 1896. 



D. albuquerquensis is one of the few American species of 

 Diaptomus in which the inner ramus of the fifth leg of the 

 female is two-segmented. In some cases this ramus, instead 

 of being bluntly triangular, is acute, and reaches only to the 

 end of the first segment of the outer ramus. The first basal 



