FAUNA OF THE CHESS AND GADE. 339 



fifth foot in the female and the male respectively. All these 

 figures were drawn from specimens taken from Langleybury Pool. 

 In fig. 27 the anterior antennae are shown as they appeared, bent 

 and twisted upwards. 



The flexibility of the long tail-setae is very great. A specimen 

 of C. staphylinus from Berkhamsted Castle Moat, obtained on 

 September 30th, 1913, was examined when confined in a very 

 small drop of water on the slide. During the vigorous struggles 

 of the animal these setae were repeatedly bent two-double without 

 breaking. Finally they snapped, after a very great number of 

 such bendings. 



The females, especially those taken during the autumn and 

 winter, are often found with a curved, reddish-brown spermatic 

 tube attached to the first abdominal segment. It was from this 

 occurrence that the generic name is said to have been given by 

 Mr. J. 0. Westwood, about the year 1835, such generic name 

 being derived from akantha kampte (curved spine). He refers to 

 his genus in ' The Entomologist's Text-book,' London, 1838, 

 p. 115, and in Partington's ' British Encyclopaedia of Natural 

 History,' London, 1836, vol. ii, p. 228 ; in each of these works 

 the genus is called " Canthocampus, having for its type C. staphy- 

 linus." The name Canthocampus seems, however, to be a mis- 

 print for Canthocamptus, and all other writers, whose works on 

 the Copepoda I have consulted, spell the generic name Cantho- 

 camptus. 



Another interesting feature of C. staphylinus is the extreme 

 flexibility of its body between the fourth and fifth segments. 

 When specimens are watched under a lens, or even by the naked 

 eye, especially when they happen to be moving over the sides or 

 bottom of the vessel containing them, they are seen to bend their 

 bodies as they swim with a peculiar jerky motion through the 

 water. Further, when they are dead, they are commonly seen 

 with their abdomen bent at a sharp angle to the rest of the body. 

 From this feature Jurine gave the specific name staphylinus to 

 this Copepod, because its caudal parts were bent after the manner 

 of the caudal parts of the staphylinus beetle. 



By some authorities on the Copepoda the species under con- 

 sideration has been called Canthocamptus minutus, Miiller. 

 Considering, however, the relative sizes of various species of 



