ANIMALIA ART1CULATA. 

 GENUS PHRONIMA, Lat. 



Four anterior pair of feet in the form of a hook; fifth didac- 

 tyle; antennae two; appendages of the tail six, styliform and 

 forked. 



GENUS TALIPRUS, Lat. 



No foot in form of a hook ; the haunch of the last pair of 

 feet very large. 



ORDER ISOPODA. 



Characteristics of the preceding order ; no palpi, however, 

 to the mandibles; seldom any proper branchiae; the first five 

 pairs of false abdominal feet branchial. 



GENUS ONISCUS, Lin. Wood-Louse. 







Four antennse (of which only the lateral ones are very 

 apparent) with eight articulations, and covered at base by 

 the lateral edges of the head ; they inhabit dark and moist 

 places. 



ARACHNIDES. 



Skin like bark, but neither horny nor calcareous ; head 

 confounded with the thorax; abdomen distinct; never wings; 

 antennae replaced by articulated pieces (chelicerae) terminated 

 by one or two movable hooks ; from two to twelve eyes grouped 

 in various ways ; never composite eyes ; generally four pair 

 of feet inserted in the thorax, and terminated by two, some- 

 times three hooks ; nervous system composed of two cords 

 which, except in the case of Scorpions, have but three gan- 

 glions; respiration by pulmonary sacs placed under the 

 abdomen, or by ramified tracheae, communicating with the 



