Marsh — North American Species of Diaptomus. 467 



"The exopodite of the fifth pair of feet of the female is two- 

 segmented, with the imguiform process of the second segment 

 slightly curved, robust, denticulate on the middle part of the 

 inner margin, the last teeth being broader and spine-like. The 

 third segment is wanting and is represented only by two spines, 

 the outer half as long as the inner. Endopodite one-segment- 

 ed, hardly equal to the first segment of the exopodite, with the 

 apex obliquely acuminate, provided with two quite long sub- 

 equal spines. 



"The second segment of exopodite of right foot in male is 

 very long, surpassing in length the first segment and the basal 

 segment taken together. The marginal spine of this segment 

 is placed within the middle. The terminal hook is slightly 

 curved, with the inner margin denticulate. The endopodite is 

 curved, ovate, broad, turning inward, mucronate at the apex, 

 hardly reaching the end of the first segment of exopodite. In 

 the left foot, the first and second segments of the exopodite are 

 setose within, the second obovate, hairy towards the apex, and 

 bearing two short spines, one of which turns inward. The en- 

 dopodite is one-segmented, slender, equaling in length the first 

 segment of the exopodite. 



"Length of female, about 1.5 mm. ; length of male, 1.4 mm." 



The above is the description as given by DeGuerne and 

 Richard. It is added that the species was found in great 

 numbers at "Multrooma Falls," Oregon. As Schacht suggests, 

 it is probable that the locality is Multnomah Falls. 



DIAPTOMUS DOKSALIS Sp. UOV. 



Plate XXIII, figs. 8, 9. Plate XXIV, figs. 2, 3, 5, 6. 



A small species. The first segment of the cephalothorax 

 considerably exceeds in length the three following. The last 

 two cephalothoracic seginents are confluent. The fifth segment 

 has two dorsal teeth, the first of which is the more prominent 

 and projects backward ; the second is rounded and undulate on 

 its anterior margin. The last segment bears two minute later- 

 al spines. 



