Marsh — North American Species of Diaptomus. 469 



ridge extends across the posterior surface of the segment. The 

 terminal hook is falciform and nearly equals in length the 

 whole right foot. The endopodite is small and slender, consid- 

 erably exceeding in length the first segment of the exopodite. 



The left fifth foot in length reaches the distal extremity of 

 the first segTuent of the exopodite of the right foot. The first 

 segment of the exopodite is somewhat longer than broad and is 

 armed on its inner margin with small hairs. The second seg- 

 ment is almost circular in outline, and also has the inner mar- 

 gin setose. It is tipped with a finger-like process and with a 

 longer slender spine. The endopodite is slender, somewhat 

 conical in shape, and reaches to about the middle of the second 

 segment of the exopodite. 



Lengtli of female, 1.1'3 mm. Length of male, 1.069 nmi. 



This species was found in collections made by Professor Birge 

 at Guzman and Milneburg, Louisiana. In the Guzman collec- 

 tions it was associated with D. mississlppiensis. The form of 

 the male fifth feet, however, and the dorsal process of the female 

 make it easy to distinguish the two species. The particularly 

 distinguishing features of D. dorsalis are the hyaline append- 

 ages of the segments of the right maje fifth foot, and this 

 dorsal process. The process very probably resembles that in 

 D. gibber Poppe, but as DeGuerne and Richard give no figure, 

 one cannot be certain. 



DIAPTOMUS SALTiLLiNus Brewcr. ' 



Plate XXIII, fig-3- 4, 6, 7, 10. Plate XXIV, fig. 1. 



1897. Diapto 1)1 us albuquerquensis Schsichty -p. 14G ; pi. XXVII, 



figs. 2, 4. 



1898. Diaptomus saltillinus 'Brevier, p. 127; pi. VII, figs. 5-9. 

 1905. Diaptomus saltillinus Pearse, p. 148 ; pi. XIV, figs. \), 



10. 



Of moderate size. The first cephalothoracic segment equals 

 in length the three following. The last cephalothoracic segment 

 is expanded in htteral lobes, each of which bears two minut« 



