224 BRITISH ENTOMOSTRACA. 



M. Siebold,* however, has had opportunities of studying 

 them carefully, and the results of his observations, with 

 his remarks on the method of copulation of Diaptomus, 

 are so interesting and striking, that I will give them here 

 at some length. The male having only the right antenna 

 provided with the swelling and hinge-joint, seizes hold of 

 the tail of the female with it, and grasping it tightly, 

 curves himself up to her ventral surface. He then sur- 

 rounds the base of her tail with the large hook of his fifth 

 pair of feet. The female is at first restless, but she soon 

 becomes more tranquil, and in this position they both fall 

 to the bottom of the water, remaining fixed sometimes for 

 hours together. The act of copulation itself, however, 

 lasts only for a short time ; but what takes place during 

 that short interval is very remarkable. " A cylindrical 

 tube, filled with a spermatic liquor, escapes from the sexual 

 organ of the male, immediately after the connection takes 

 place ; the male seizes this tube as soon as it has made its 

 exit, and fastens it against the abdomen of the female, be- 

 neath the vulva, "t The fifth pair of feet is most probably 

 the organ by which the male seizes the tube ; but Siebold 

 did not distinctly ascertain the fact. When it escapes 

 from the male organ, it is by its rounded extremity ; and 

 it would appear, that when the animal lays hold of it, he 

 presses the neck of the tube with the tip of his foot against 

 the first joint of the tail of the female, and as the neck of 

 the tube contains a glutinous substance, it immediately 

 adheres. 



Such is the operation, as described by Siebold from 

 personal observation, and from which he concludes, that it 

 is with the matter in these tubes that the female is fe- 

 cundated. No female, he says, possesses a tube before 

 copulation ; but immediately after the act is accomplished 

 we see one fastened to her, near the vulva. If a male 

 be examined, when in heat and before copulation take 



* Mem. de la Soc. des Scrutateurs de la Nature, de Dantzig, iii, part ii, 

 1839 ; Ann. des Sc. Nat., 2d ser., xiv, 26-38, 1840. 

 t Ann. des Sc. Nat., xiv, 28. 



