STATE GEOLOGIST. 157 



II. — Fifth Foot 1- join ted. 

 Sp. 23. Cyclops varicans, Sais. 



"Cephalothorax ovate, attenuated about equally in front and be- 

 hind, with the last segment wider than the abdominal segments, 

 produced laterally and bearing a long seta. Abdomen elongate; 

 caudal rami scarcely as long as last two segments; the internal 

 apical seta twice as long as the outer; median pair elongated, the 

 internal one as long as the abdomen. Antennae 12-joiuted, robust, 

 shorter than the first thoracic segment. ^ ,!. Both rami of swimming 

 feet tv/o-jointed. ^ ^ Feet of fifth pair rudimentary, with a single 

 linear segment bearing a long spine. Ova-sacs long, divergent. 

 Length 1 mm." 



Very possibly the young of some species not now identifiable. 

 Only mentioned by Sars. (Compare C. diaphanus below.) 



Sp. 24:. Cyclops serrulatus, Fischer. 



(Plate 0. Figs. 17—19.) 



? Cyclojis agiJis, koch (fide Rehberg). 



Cyelopg serrulatus, lill.teborg, claus, sar3, lubbock, heller, fric, hoek, brady; 



Cyclops longieornis, vernet. 



Cyclops pecUnifer, cragix. 



Although Rehberg positively asserts that Koch's name applies to 

 the present species, none of the numerous authors who have men- 

 tioned this most widely distributed form have employed any other 

 than the familiar designation, and the practical advantage to be 

 derived from its use seems to outweigh a quibble of doubtful 

 synonymy. 



Cephalothorax oval, compact; abdomen slender and short, sud- 

 denly enlarged previous to its union with the thorax; antennae 

 slender, reaching nearly, but not quite to the last thoracic segment; 

 the last three joints are attenuated and furnish the most evident 



character of the species; formula — :=r^ — ^^:r — -^ ; during 



life the antenna3 tend to assume the form of a rude Z, the proximal 

 four joints forming the base; antennules small, reaching about to 

 the sixth joint of antenute; jaws small with large teeth; the single 

 segment of the fifth foot with three equal spines; egg-sacs oval, as 

 long as the abdomen; eggs few, dark; caudal stylets very long and 

 slender, spined along the outer margin; lateral setae small and ap- 

 proximated to the upper one; outer terminal seta short, spine-like, 

 in life set nearly at right angles to the others, spined or beaded 



