430 



R. 1. FOCOOK. 



trochanter of the posterior legs with the femur, the pi'esence 

 of prtesternal sclerites, etc., renders unavoidable the conclusion 

 that the twenty-one terga in the two forms are homologous 

 plate for plate. Assuming that this is so, and that the 

 opinion given above touching the supernumerary terga is also 

 correct, it follows that the passage from the Scolopendroid 

 type, with twenty-one complete somites, to the Lithobioid 

 type, with fifteen complete somites, was effected by the ex- 

 calation of the third, sixtli, ninth, eleventh, fourteenth, and 

 seventeenth somites of the former type. This new explanation 

 of the connection between the metamerism of the two types is 

 illustrated in the annexed diagrams (p. 433), and may be 

 tabulated as follows : 



ScOLOrENDROID TyPE. 



1 major and astigmous represents . 



2 minor and astigmous represents . 



3 major and stigmaliferous. 



4 minor and astigmous represents . 



5 major and stigmatiferous represents . 



6 minor and astigmous. 



7 major and astigmous or stigmatiferous 

 represents .... 



8 major and stigmaliferous represents 

 y minor and astigmous. 



10 major and stigmatiferous . 



11 minor and astigmous. 

 1'2 major and stigmatiferous represents 



13 minor and astigmous represents 



14 major and stigmatiferous 



15 minor and astigmous represents 

 10 major and stigmatiferous represents 



17 minor and astigmous. 



18 major and stigmaliferous represents 



19 minor and astigmous represents 



20 major and stigmatiferous represents 



21 minor and astigmous represents 



22 genital represents 



23 anal represents 



Lithobioid Type. 



1 major and astigmous or 



stigmatiferous. 



2 minor and astigmous. 

 Excalated. 



o major and stigmatiferous. 

 ■4 minor and astigmous. 

 Excalated. 



5 major and stigmatiferous. 

 G minor and astigmous. 

 Excalated. 



7 major and astigmous. 

 Excalated. 



8 major and stigmatiferous. 



9 minor and astigmous. 

 Excalated. 



10 major and stigmatiferous. 



11 minor and astigmous. 

 Excalated. 



12 major and stigmatiferous. 



13 minor and astigmous. 



14 major and sligmatiferous. 



15 minor and astigmous. 

 10 genital. 



17 anal. 



If the theory here set forth be in accord with fact, it is 



