234 HANDBOOK OF INVERTEBRATE ZOOLOGY. 



fastened by the cement, until the discharging bodies drive 

 the spermatozoa into the seminal receptacle. Males and 

 females may occasionally be found while copulating ; and 

 if they are examined with a lens, the male may be seen to 

 clasp the thoracic limbs or abdomen of the female with his 

 jointed antennae, and then, bending up his body, deposit 

 a spermatophore upon the external median aperture of the 

 seminal receptacle. This spermatophore adheres to the 

 body of the female, and the spermatozoa are absorbed 

 into the inland, and each time that eggs are laid a sufficient 

 number pass up through the ducts already noticed to fer- 

 tilize them. It is probable that one impregnation senses 

 for the whole life of the female. At any rate, one connec- 

 tion with the male serves to fertilize several broods of 

 effsfs. 



Fig. 126. — Spermatozoa of Cyclops tenuiconiis, 

 highly magnified. (From Graber, Taf. xxv., Fig. 2.) 

 Fig. 126. 



Place two or three egg-bearing females in a large watch- 

 crystal full of water ; cover this with another crystal, or 

 with a glass tumbler, and set it aside until the eo:o:s hatch. 

 Then carefully examine the water around the edges of the 

 crystal for the very minute and active young. Having 

 found a specimen, catch it with a dip})ing-tube, and trans- 

 ferring it to a glass slide, examine it with a power of two 

 hundred and fifty to three hundred diameters. 



VI. The J^auplius Stage. The newly-hatched larva 

 of a Copepod is known as Nauplius. It has an oval body 

 (Fig. 127), and three pairs of jointed locomotor append- 

 ages, and presents the following points for examination. 



a. The middle of the ventral surface of the body is 

 occupied by a large oval labrum (Fig. 127, L), through 

 which the opening of the mouth may be seen. 



