346 Dr. Crampton on Insectan & Myriopodan Structures. 



As a filial point in the discussion of the interpretation 

 of insect morphology in the hght of a comparison with 

 Crustacean structures, I would emphasise the fact that 

 in every instance the condition met with in the Crustacea, 

 rather than that occurring in the Myriopoda, has offered 

 the key to the solution of the meaning of the parts in 

 insects ; and the series of studies have convinced me 

 that insects are anatomically intermediate between the 

 higher Crustacea on the one side, and the Myriopoda 

 (such as Scolofendrella, Pauropus, etc.) on the other. 

 The Hnes of development of the lower insects such as 

 Campodea, etc., which resemble Scolop>endrella, and other 

 Myriopoda, however, appear to end in a " cul de sac " 

 leading nowhere ; while the lines of development of the 

 apterygotan insects nearer the Crustacea {e.g. Machilis, 

 Lepisma, Nicoletia, etc.) are those which lead to the de- 

 velopment of the pterygotan type of insect, and the lowest 

 winged insects such as the mayflies have carried over a 

 surprisingly large number of " crustaceoid " characters, 

 particularly in the immature stages. I would further 

 point out that Machilis is anatomically a far more primi- 

 tive insect than is usually supposed to be the case, and 

 in many instances it has furnished the connecting hnks or 

 intermediate stages enabUng one to compare the struc- 

 tures of the Ephemerids and other lower winged insects 

 with those of the Crustacea. 



