A XUW AND ANNKOTANT TYPE UP CHiLOPOD. 427 



stigmata; the fusion of the sternal and pleural sclerites of the 

 penultimate and antepenultimate somiteSj and the complete 

 coalescence of the tergal, pleural, sternal, and pi-a3sternal 

 elements of the last somite to form a compactly chitinised 

 subcyliudrical tube; the distinctness of the coxa of the 

 postei-ioi' leg', coupled with its articulation to the posterior 

 extremity of the somite and the fusion of the trochanter 

 with the femur; the representation of the external skeletal 

 elements of the genital and anal somites by a pair of valves 

 fused dorsally, but opening ventraliy by a long slit-like 

 aperture, whence the genital and anal products escape to the 

 exterior. 



The above-given comparisons demonstrate the impos- 

 sibility of associating Craterostigmus with either of the 

 groups of Chilopoda hitherto recognised, and substantiate 

 its claim to take a rank at least as high as that which is 

 assigned to the others individually, call them families, 

 sub-orders, orders, — what you will. 



Part III. — The Testimony supplied by Obaterostigmus 

 AS to the Descent oe the Lithobiomorpha from the 



SCOLOPENDROMORPHA. 



Apart from the characteristics peculiar to itself, which 

 present us with new facts in Chilopod morphology ; apart, 

 too, from those that it shares with either one or more of the 

 previously known divisions of this class of Arthropods, the 

 chief point of interest vested in Craterostigmus lies in the 

 explanation it furnishes of the principal resemblances and 

 differences obtaining between the Lithobiomorphous and 

 Scolopendromorphous types of structure, and also in the 

 new and wholly unexpected light it throws upon the 

 metamerism of these two types, enabling us to picture 

 the procL'Ss by which the one has been converted into the 

 other. 



Except for the numerical difference, the somites of 

 Lithobius and Scolopendra exhibit certain obvious and 



