608 



ZOOLOGY 



SECT. 



these it is carried by a series of veins to the pericardial sinus to 

 enter the heart through the ostia. 



The organs of respiration in the Scorpions are in the form of 

 pulmonary sacs or book-lungs (pul.), the stigmata or external openings 



of which have already been referred to. Each pulmonary sac is 

 a compressed chamber lined with a thin cuticle. The lining 

 membrane is raised up into numerous delicate laminae lying 

 parallel with one another like the leaves of a book. Into the 



