416 Wisconsin Academy of Sciences, Arts, and. Letters. 



DIAPTOMUS PALLIDL'S Ileri'ick. 



Plate XVT, figs. 1, 2, 3. 



1879. Diaptomus pallidus Herrick, p. 91 ; pi. II, figs. Ord. 



1883. Diaptomus pallidus Herrick, p. 383; pi. VII, figs. 1-6. 



1884. Diaptomus pallidus Herrick, p. 142 ; pi. Q, fig. 17. 

 1889. Diaptomus pallidus DeGuenie and Richard, p. 62 ; fig. 



34. 

 1893. Diaptomus pallidus Marsh, p. 196 ; pi. Ill, figs 6, 7, 9. 

 1895. Diaptomus pallidus Herrick and Turner, p. 73 ; pi. IV, 



figs. 1-6; pi. V, fig. 10; pi. XIII, fig. 17. 

 1897. Diaptomus pallidus Schacht, p. 144 ; pi. XXVII, fig. 3. 

 1905. Diaptomus pallidus Pearse, p. 147. 



A slender species of medium .size. First cephalothoracic 

 segment considerably longer than the three following; the last 

 cephalothoracic segment bears two small lateral spines. 



The first abdominal segment of the female nearly equals in 

 length the rest of the abdomen, is slightly dilated laterally, and 

 bears two minute lateral spines. The second segment is slightly 

 shorter than the third, and the third slightly shorter than the 

 furcal rami. The furcal rami are ciliate on the inner margin. 



The antennae are 25-segmented and reach slightly beyond 

 the end of the furcal rami. The right antenna of the male is 

 swollen anterior to the geniculating joint, and without special 

 armature. 



The female fifth feet are short and stout, the spines of the 

 first basal segments small. The lateral hairs of the second 

 basal segments are rather long. The oxopodite is composed of 

 two segments, the third segment being repres^ted by two 

 spines. The second segment is prolonged into a rather long 

 hook, and serrulate on the inner margin. The endopodit« is 

 slightly longer than the first segment of the exopodite; the tip 

 is setose, and armed with two rather long spines. 



In the male fifth foot the spines of the posterior surface of 

 the first basal segments are small. The second basal segment 



