On Synthetic Types in Insects. G93 



"What have we now in common with both, and which 

 shall reunite this seeming polarity in llie two series of 

 sub-orders? There is needed a group which, while retain- 

 ing its own strong fundamental features, and maintaining 

 an equal footing with its equivalent groups, shall have 

 besides the strongest analogies to those groups fartlicst 

 removed by alfinity, in order that these two series may 

 be virtually brought together; while the successive forms 

 in the several families shall afford us some conception 

 of the larger categories these minor groups foreshadow. 

 Such a group Professor Agassiz * has pointed out in the 

 class of Selachians, which combine the characters of all 

 the otiier classes of fishes existing during the same period, 

 and also, by their being the earliest in time, afford what 

 he calls prophetic types of all the coming classes of ver- 

 tebrates. The former case affords what he calls synthetic 

 types. 



In endeavoring to show that a similar Synthesis among 

 insects has its seat in the Neuroptera, I would in the first 

 place instance the genus Lepisma, one of the Thysanoura 

 which Burmeister places among the Orthoptera, and which 

 also reminds us of the larvae of Perla and Ephemera. In 

 the scales which clothe the body of Lepisma we are re- 

 minded of the squamation of the Lepidoptera ; but we 

 mention this group now, in order to point out some strong 

 analogies they bear to the chilopodous Myriapods. This is 

 seen in their elongated, flattened form, which is due to the 

 uniformity in the size of the rings of the three divisions of 

 the body, by which the distinctions of the head, thorax, 

 and abdomen seem almost annulled; and in the fact 

 that while Lepisma does not differ greatly in size from 

 the small genus Scolopendrella, it agrees also in the 

 semi-oval head, in the anal stylets, so unusual in the 

 Myriapoda, and especially in the two pairs of little, move- 



* Essay on Classification. 



JOUKNAl. 1!. S. X. II. 75 



