1916] Thoracic and Cervical Sclerites of Insects 45 



found in diplopods, Scolopendra, Geophiliis and Scolopendrella. 

 He thinks that the pre-segmental chitinous plates in insects 

 are a secondary differentiation, explainable by mechanical 

 causes as represented in lampyrid larvae. 



Enderlein, '07, regarded the complementary segments in 

 Japyx, which correspond to Verhoeff's micro-, steno-, and 

 cryptothorax as " constricted-off " portions of the pro-, meso-, 

 and metathorax and terms them the apotom of their respective 

 segments. That is to say, they are detached portions of the 

 pro-, meso-, and metathorax. 



Desguin, '08, attacks Verhoeff's theory and shows that 

 embryology, anatomy, musculature, etc., give no evidence 

 in support of it. Other writers have criticized Verhoeff's 

 ideas and it has been shown that all the facts seems to be 

 contrary to his views. Unless further evidence is brought 

 forth to substantiate Verhoeff's theory of the composition of 

 the insect thorax it must be regarded as untenable. 



Henneguy, '04, reverts to Kolbe's theory and expresses 

 similar ideas. He finds in the larva of Lampyris, that each 

 tergum covers two ventral "segments," the first of which bears 

 a pair of spiracles and is known as the complementary segment, 

 while the second segment bears a pair of legs. He finds these 

 same conditions in Scolopendrella and from this concludes, 

 first, that the Myriopoda are ancestors of insects; second, 

 that the present position occupied by the spiracles in adult 

 insects is explainable on the ground, that they are borne on 

 the complementary segments. Henneguy finds traces of com- 

 plementary segments in the thoracic region of elaterid and 

 staphylinid larvae and in the abdominal region of carabid 

 larvae. He finds that in the larva of Raphidia, the comple- 

 mentary segment between the pro-, and mesothorax, is a com- 

 plete segment. The larvae of some Diptera appear to have double 

 the number of segments present in other larvae of the same 

 family, each complementary segment being produced by a 

 transverse constriction of such a nature, that a sort of inter- 

 mediate segment is formed between the normal segments. 

 Henneguy states, that according to Brauer, this arrangement 

 is due to a lengthening of the membrane uniting two con- 

 secutive segments, or to a secondary constriction of each 

 annulus. 



