Chap. VI.] 



ARACHNIDA. 



227 



the oxygen to the blood. Among the Arachnida, thb 

 remarkable series of changes so far followed does not 



Fig. 97. A. View of the lower Margin of the right lamelliferous Appen- 

 dages of the eleventh segment of Limulus polyphemus. 



A. I, Proximal lamella ; lx, one hundred and fiftieth lamella ; ex, external lappet of 



the bifld distal prolongation of the appendages. 

 B. A similar view of the corresponding appendage of Buthus fcocTii. 



lx, One hundred and thirtieth lamella ; 

 c. A. semi-diagramatic view of one of the respiratory Appendages of a 



Scorpion, to show 



I, The bases of the lamellce exposed by the removal of the integument of 

 the axis, the remnants of which are seen at TO : oc, the projecting portion of 

 axis ; I, proximal lamella. (After E. Ray Laukester.) 



end with the scorpion ; some, like Mygale, have but 

 two pairs of lung-books, and other spiders have but 



