CHAPTER XIII. 



HINTS ON THE ANCESTRY OF INSECTS. 



THOUGH our course through the different groups of insects 

 may have seemed rambling and desultory enough, and pursued 

 with slight reference to a natural classification of the insects of 

 which we have spoken, yet beginning with the Hive bee, the 

 highest intelligence in the vast world of insects, we have gradu- 

 ally, though with many a sudden 

 step, descended to perhaps the 

 most lowly organized forms 

 among all the insects, the para- 

 sitic mites. While the Demodex 

 is probably the humblest in its 

 organization of any of the insects 

 we have treated of, there is still 

 another mite, which some emi- 

 nent naturalists continue to re- 

 gard as a worm, which is yet lower 

 in the scale. This is the Pentas- 

 toma (Fig. 177, P. tsenioides;, 

 which lives in the manner of the 

 tape worm a parasitic life in the 

 higher animals, though instead of 

 inhabiting the alimentary canal, 

 the worm-like mite takes up its 

 abode in the nostrils and frontal 

 sinus of dogs- and sheep, and sometimes of the horse. At first, 

 however, it is found in the liver or lungs of various, animals, 

 sometimes in man. It is then in the earliest or larval state, and 

 assumes its true mite form, being oval in shape, with minute 

 horny jaws adapted for boring, and with two pairs of legs armed 

 (148) 



177. Pentastoma. 



178. Centipede. 



