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- 



gai'd as a worm, which is yet lower 



in the scale. This is the Peutas- 



toma (Fig. 177, P. tsenioidesj, 



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 tlie 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, aud with two pairs of legs armed 

 (148) 



177. Pentastoma. 



178. Centipede. 



