AEACHNIDA. 643 



form of (2) a hexapod larva, followed by the stage of (3) octo- 

 pod irymphse [four-footed pupae], without sexual organs. (4) 

 From some of these nymphaj issue : a, sexual males, after a 

 moult which is final for them ; 6, from others issue females 

 without external sexual organs, resembling the nympha?, but 

 larger, and in some species furnished with special copulatory 

 organs. Finally, after a last moult following copulation, these 

 females produce (5) the sexual and fecundated females, which 

 do not copulate, and in the ovary of which eggs are to be seen. 

 No moult follows that which produces males or females fur- 

 nished with sexual organs ; but previously to this the moults 

 are more numerous than the changes of condition." " The larvae 

 undergo from two to three moults before passing t6 the state 

 of nymphae." These latter also undergo two or three moults. 

 (Annals and Magazine of Natural History, 1868, p. 78.) 



In some other species of mites no males have been found, 

 and the females have been isolated after being hatched, and 

 yet have been known to lay eggs, which produced young with- 

 out the interposition of the males. This parthenogenesis has 

 been noticed in several species. But few fossil Arachnids 

 have been yet discovered. Roemer has described a spider 

 from the coal formation of Germany under the name of Proto- 

 lycosa, while two species of scorpions, and a Phalangium-like 

 spider have been detected in the same formation in this 

 country. 



In studying spiders, of which we have several hundred spe- 

 cies, the number and relative situation of the eyes, and the 

 relative length of the different pairs of legs, should be noticed ; 

 their webs and the manner of constructing them ; their habi- 

 tats, whether spreading their webs upon or in the ground, or 

 in trees, or on herbage, or whether the species are aquatic, or 

 erratic, and pursue their prey without building webs to entrap 

 them, should be observed. So, also, how they deposit their 

 eggs, and the form and appearance of the silken nidus, and 

 whether the female bears her eggs about her, and how this is 

 done, whether holding on to the egg-sac by her fore or hind 

 legs, should all be carefully noticed. Care must be taken not 

 to mistake the young for full-grown, mature species, and de- 

 scribe them as such. Spiders can be reared in boxes as 



