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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 75 



and the " wings " of the last cephalothoracic segment. Figure 16. The 

 material has shown certain minor differences from Schacht's descrip- 

 tion. The lateral spines of the first segment of the female abdomen 

 are not " large " but of moderate size. The f ureal rami are ciliate on 

 outer as well as inner margins. 



There is considerable variation in the form of the endopodite of the 

 left fifth foot of the male. In the figure of Herrick, in 1882, cross 

 striae or partitions are shown. In 1884 Herrick says that the '' inner 

 ramus is marked with oblique ridges," and these are shown in his fig- 

 ure. Herrick and Turner, in 1895, say that " it is corrugate inter- 



FlGURES 13-16.— 13, DiAPTOMUS STAGNALIS FOBBES, TERMINAL SEGMENTS OF 

 RIGHT ANTENNA OF MALE; X 307. 14, DiAPTOMUS STAGNALIS FORBES, FIFTH 

 FOOT OF male; X 109. 15, DIAPTOMUS STAGNALIS FORBES, FIFTH FOOT OF 



female; X 307. 16, Diaptomus stagnalis Forbes, showing wings of 



LAST cephalothoracic SEGMENT OF FEMALE; X 5.5 



nally," and their figures show corrugations on the outer margin. 

 Schacht, in 1897, says " inner margin rugose." In the specimens ex- 

 amined by the author these markings which are striations rather 

 than corrugations vary in their distinctness and in number. 

 Sometimes there are not more than three or four; at others 

 there may be six or more. In some cases they cross the endopodite 

 at right angles, while in others they are oblique. In none of the 

 individuals examined were they distinct enough to warrant the 

 use of the words " rugose " or " corrugations." The appendages 

 of the terminal segment of the left exopodite consist of an outer 



