418 



ZOOLOGY. 



seen takes place in the Crustacea ( 111). In the arachnida 

 which breathe only by trachese, the apparatus of the circula- 

 tion is rudimentary. There appears to be merely a simple 

 dorsal vessel without arteries or veins. 



557. The arachnida lay eggs like insects, and the male 

 differs generally from the female in the form of the maxillary 

 feelers, the uses of which appear to be very important. A 





Fig. 414. Anatomy of a Mygale.* 



great number of these animals envelope their eggs in a 

 cocoon of silk, and sometimes the mother remains near her 

 young family to protect it, and even carries the little ones on 



* ct, cephalothorax open below, and giving attachment to the limbs, 

 the baee of which is in place; pa, limb of the first pair; , feeler; m, 

 mandibles ; ab, abdomen ; t, thoracic ganglionary mass ; a, abdominal gan- 

 glions ; po, pulmonary pouches ; , stigmata ; /, respiratory lamellar of One 

 of its cavities, laid open ; o, the ovaries ; or, orifice of the oviducts ; ma, 

 muscles of the abdomen j a., anus ; f t winders. 



