CYCLOPIDJE. 189 



appears to be this form. The variety speratns, which has 

 the t'urcal joints moderately Ion;} and proportionately more 

 slender, has been noticed in gatherings from a pond at 

 Kingsteignton, Slapton Lea, and the canal at Newton Abbot. 

 The typical C. serrulatus appeared to be less frequent than 

 were the varieties referred to, hut the points which dis- 

 tinguish C. varius from C. serrulatus are so minute as to 

 indicate a very close relationship between them ; and, more- 

 over, as C. varius itself comprises no fewer than three 

 varieties, we have thought it best, having indicated the 

 different varieties observed, to retain them all under the 

 specific name established by Fischer. 



CYCLOPS PRASINUS, Fischer. (PI. XXI. figs. 9-11.) 



1860. Ci/clops prasinus, Fischer, " Beitr. z. Kenntn. d. Entom.," 

 Abliand. d. bayer. Akad. d. Wiss. Miiuchen, vol. via. p. 652, 

 pi. xx. tigs. 19-20 a. 



1892. Cyclops prasinus, Schmeil, I. p. 150, pi. v. figs. 1-5. 



Slapton Lea, Devon, in June 1904 ; and a moor pond near 

 the middle of some waste ground at ISt. Erth, Cornwall, 

 in this gathering the species was moderately abundant. 

 (PI. XXI. figs. 9, 10, 11, are drawings of the antennule, foot 

 of fifth pair, and of the abdomen and furcal joints.) 



CYCLOPS VENUSTUS, sp. n. (PL XVI. fig. 11 ; PI. XVIII. 

 fig. 9 ; and PI. XX. figs. 1-3 ) 



The species described below resembles Cyclops vernalis, 

 Fischer, in its general appearance and size and in the 

 structure of the fifth pair of thoracic feet, but differs very 

 distinctly in the structure of the antennules. 



The length of the female represented by the drawing 

 (PL XX. fig. 1) measures I'-l mm. (nearly ^ of an inch), 

 exclusive of the tail setae. 



The antennules, which are moderately stout and composed 

 of twelve joints, scarcely reach beyond the end of the cephalo- 

 thoracic segment (PL XX. fig. 2). The third and sixth 

 joints are very small, while the first, eighth, and ninth are 

 considerably larger than any of the others, as shown in the 

 annexed formula, which exhibits approximately the pro- 

 portional lengths of all the joints : 



Proportional lengths of 



the joints 30 . 7 . 5 . 9 . 8 . 5 . 9 . 20 . 16 . 9 . 11 . 12 



Numbers of the joints. . 1 2 y 4 5 (J 7 8 9 10 11 12 



The mouth-organs and swimming-feet are similar to the 

 same appendages in Cyclops rcrnalis. The rudimentary fifth 



