AttT. 18 SYNOPSIS OF CALANOID CRUSTACEA MARSH 29 



In the right fifth foot of the male tlie endopod may be rudimentarj 

 or lacking; the exopod has two or three segments with a terminal 

 hook. In the left foot the endopod may be present or lacking; the 

 exopod is 2- or 3-segmented. 



Some of the species are reported as having two egg sacs and some 

 as having onlj^ one. It is known that in P. coronatus, culebrensis, 

 and 7'^ichardi, although there are two sacs, only the left is fully 

 developed, the right one being aborted. It seems probable that in 

 the species reported with one sac this may be considered as the left, 

 and possibly a more careful study may show indications of the right 

 one. 



Occurrence. — The genus P send od in pt onus has not been reported 

 from European waters. Seven species occur in America, all but one, 

 P. culehrensis, from waters connected with the Atlantic. Three 

 are in South America in the Amazon or La Plata. Two are found 

 in North America, P. coronatus on the New England coast and in 

 Chesapeake Bay, and P. felagicus in Mississippi Sound. P. pelagi- 

 aus, which was described as the type of the genus by Herrick in 

 1884, has never been collected by anyone eise. Two species were 

 found in the Canal Zone. Species of Pseud odiaptoinus have been 

 found on both coasts of Africa, in the Red Sea, the Indian Ocean, 

 Burma, and the East Indies. 



KEY TO THE SPECIES OF PSEUDODIAPTOMUS 



1. No endopods on male fifth foot 2 



Endopods on both male fifth feet 3 



Endopods on right male fifth foot only aurivilli Cleve*^ 



Endopods on left male fifth foot only 6 



2. Last thoracic segment of female rounded ; a long falciform hook 



terminating second segment of exopod of fifth foot, nearly as 



long as exopod gracilis (Dahl) 



Last thoracic segment of female with pointed wings ; second 

 segment of exopod of fifth foot terminated by two broad, 

 nearly equal spines, which are about one-half as long as 

 exopod clevei A. Scott 



3. Last thoracic segment in female rounded hessei (Mrazek) 



Last thoracic segment in female with pointed wings 4 



4. Right endopod of male fifth foot not bifid__ stuhlmanni (Poppe and Mrazek) 

 Right endopod of male fifth foot bifid 5 



5. Terminal hook of female fifth foot and inner spine equal in 



length ; second segment of left exopod of male fifth foot trun- 

 cated at distal end hickmani Sewell 



Terminal hook of female fifth foot longer than inner spine ; 

 second segment of exopod of male fifth foot pointed at distal 

 end saliuus (Giesbrecht) 



6. Left exopod of male fifth foot 1-segmented acutus (Dahl) 



Left exopod of male fifth foot 2-segmented 7 



^ Synonym : P. mertoni Friichtl. 



