612 SUMMARY OF CURRENT RESEARCHES RELATING TO 



insertion of a certain number of delicate quadrangular lamellae, only 

 fixed along the edge /3 y. If the animal passes to a terrestrial mode 

 of life the flaccid lamellae, which were previously supported by the 

 water, will apply themselves to one another, and will only be very 

 imperfectly in contact with the air. They will become attached by 

 their faces. [The three diagrammatic figures represent the modifica- 

 tions which have probably been undergone by the gill of a Limulus in 

 becoming converted into the lung of a scorpion, a Limulus, b an 

 intermediate stage, c a scorpion, st sternal plate, A B C D respiratory 

 limb, attached by A B to the sternal plate, a jB y 8 respiratory lamella. 

 The dotted lines indicate where fusion has taken place, the black ones 

 the presence of a free chitinous edge a /3 and y 8 to the wall of the 

 depression in which they are placed. The chitinous plate (modified 

 limb) which covers them will fuse by its external edge C D to the 

 edges of this depression.] 



Jjimuli 

 (Five pairs of branchiferous appendages) 



Passage to terrestrial mode of life. The first pair of respiratory 



limbs loses its function. The four following are adapted to 



aerial respiration. 



Scorpions 

 (The two hinder lungs disappear) 



Telyphonws. The rings of the abdomen fuse. 



Tetrapneumones . 



The second pair of lungs converted into tracheae. 



I 

 Dipneumones. 



In conclusion, doubt is thrown on the protracheate nature of 

 Peripatus, and the suggestion is made that the respiratory organs of 

 the Arachnida are not homologous with those of the Insecta. 



Habits of Scorpions.* — Professor E. Bay Lankester records some 

 interesting observations which he has recently undertaken on Androc- 

 tonus funestus and Euscorpius italicus. 



Of Androctonus he relates their mode of burrowing in sand, 

 making horizontal tunnels which are often as much as 8 inches 

 long. They commence by pushing the large chelee into the sand and 

 scraping very rapidly backwards with the three anterior pairs of 

 walking-legs, this use of the legs comparing with the parallel but not 

 identical use of the legs in Limulus. They were evidently timid, 

 hiding in the daytime. Their carriage is remarkable, as in walking 

 they raise their body well from the ground, the tail reflected over the 

 back, and the sting carried just over the cephalic shield ready to give 



* Journ. Linn. Soc. (Zool.) xvi. (1882) pp. 455-62 (3 figs.). 



