A NEW AND ANNKCTAiNT TYPE OF CHILOPOD. 42 9 



on this point is to be held. But the stigmata in Cra- 

 terostigmus lie beneath the fourth, seventh, twelfth, 

 fifteenth, eighteenth, and twentieth tergal plates ; whence it 

 follows that these tergal plates are the dorsal elements of 

 the somites bearing the third, fifth, eighth, teuth, twelfth, 

 and fourteenth pairs of legs. That is to say, Cratero- 

 stigmus, as compared with Li th obi us, has one extra 

 tergal plate without sternal or appendicular representative 

 between the first and third pediferous somites, one between 

 the third and fifth, two between the fifth and eighth, one 

 between the eighth and tenth, and one between the tenth 

 and twelfth, making in all a total of six. Which are these 

 supernumerary terga ? the second or the third ? the fifth 

 or the sixth ? which two of the eighth, ninth, tenth, and 

 eleventh ? the thirteenth or fourteenth ? the sixteenth or 

 seventeenth ? 



The answers to these questions are not at first sight 

 easily given, owing to the difficulty of deciding which of 

 two terga overlying a sternum is its representative on the 

 dorsal area. Cai-eful examination, however, of the nature 

 of the folds and the development of sclerites iu the pleural 

 integument shows that the terga without sternal comple- 

 ments are the third, sixth, ninth, eleventh, fourteenth, and 

 seventeenth, these being the plates beneath which the repre- 

 sentatives of the metastigmatic pleui-al sclerite is scarcely 

 or not at all developed. Moreover the third, sixth, eleventh, 

 and fourteenth terga are overlapped posteriorly by the 

 terga that lie behind them ; the ninth does not overlap 

 the anterior border of the tenth; and the seventeenth, 

 although overlapping the eighteenth in the normal manner, 

 does not overlie the prtecoxal sclerite of the eleventh 

 pediferous somite, but is, as it were, wedged iu between the 

 tergum of this and of the following somite. 



In the second place, the similarity between Craterostig- 

 mus and Scolopendra in the structure of the maxillse, 

 palpognaths, and toxicognaths, in the number of antennal 

 segments, the equality in size of the coxas, the fusion of the 



