AET. 18 SYNOPSIS OF CALANOID CRUSTACEA MAESH 39 



PSEUDODIAPTOMUS KICHARDI (Dahl) 



Plate 20, Figxtres 1, 3 



Weisiiwuella richardl Dahl, 1894, p. 11, pi. 1, figs. 6-S. 



Schmackeria Hchardi Poppe and Mrazek, 1895, ]). 5. 



Pseudodiaptomus richaidi Giesbrecht and Schmeil, 1898, p. 64. — Mrazek, 



1901, p. 14, figs. 14, 29.— Pesta, 1927, p. 71, fig. 2, h-d. 

 Pseudodiaptomus richardi var. inaequalis Brian, 1926, pp. 187, 188, figs. 15, 16. 



Fernale. — The head is not directly separated from the thorax. 

 The sides of the last thoracic segment are rounded. The abdomen 

 has four segments and the distal borders of the segments do not 

 have spines. The fiircal rami are short. The first antennae have 

 20 (21 according to Brian) segments and reach the second abdominal 

 segment. The fifth feet (pi. 20, fig. 3) are much like those of P. 

 pelagicus and P. coronahts, the terminal segment having, besides the 

 hook, a small acute external spine, and a stout internal spine. The 

 left egg sac is much more developed than the right, containing 10 

 to 12 ova, while the right has 4 or 5. 



Length, 1.4 mm. 



Male. — The right fifth foot (pi. 20, fig. 1) resembles closely that 

 of P. coro7iatus, but does not have the stout spine that in P. coro- 

 natus is found on the first segment of the basipod. It has the flask- 

 shaped spine on the first segment of the exopod which is found in 

 coronatus ; this is shown in Dahl's figure and in the figure of Brian's 

 variety inaequalis. The left foot has an endopod extending to about 

 one-half the length of the second segment of the exopod. The first 

 segment of the exopod is short, the second about as long as broad. 

 The second segment of the exopod is truncate at the distal end; the 

 distal margin is dentate ; there is a slender curved spine at the inner 

 distal angle and at the base of this spine a short stout spine. 



Length, 1 mm. 



Occurrence. — Found in brackish water at the mouths of the Ama- 

 zon, the La Plata, and the Parana Rivers. 



Remarks. — P. richardi var. inaequalis Brian differs from the type 

 in that the last thoracic segment of the female is prolonged back- 

 ward into lobes, which are armed with spines. 



PSEUDODIAPTOMUS SALINUS (Giesbrecht) 



Plate 20, Figures 4, 5 



Hchmackeria salina Giesbrecht, 1896, pp. 322, 323, pi. 6, figs. 23-28. 

 Pseudodiaptomus salinus Giesbrecht and Schmeil, 1898, p. 65. — Thompson and 

 Scott, 1903, p. 248, pi. 2, figs. 21-23. 



Female. — The head is not distinctly separated from the thorax. 

 The wings of the last thoracic segment are pointed. The abdomen 



