STATE GEOLOGIST. 15T 



II. — Fifth Foot I-joii^ted. 

 Sp. 23. Cyclops varicans, Sars. 



"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-jointed, robust, 

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

 feet two-jointed. ^ ^ Feet of fifth pair rudimentary, with a single 

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

 Length 1 mm." 



Yery 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.) 



? Cyclops agilis, koch (flde Rehberg). 



Cyclops serrulatus, lilljeborg, claus, sars, lubbock, heller, fric, hoek, brady. 



Cyclops longicornts, vernet. 



Cyclops pectinifer, 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 — ^^ — ^^^ — ^ ; during 



life the antennae 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 antennae; 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 on 



