OF THE ANNULOSA. 401 



animals, for instance, are so singular in appearance as the 

 geometrical larvae of the Phalanida* ; and the only place 

 where we shall again meet with this mode of progression 

 among the Annulosa is at the corresponding point of the 

 Crustacea, that is, between the types of the Lcemodipoda 

 and Isopoda, as the geometrical Caterpillars occur be- 

 tween the types of the Lepidoptera and Homoptera. 



A natural series of affinity is such as, taking the ma- 

 jority of characters for our guide, shall be found uninter- 

 ru pted by any thing known, although possibly broken by 

 chasms occasioned by the absence of things unknown. 

 Thus the series of the Sy sterna Natwa and of the Regne 

 Animal is not natural when the Cetacea intervene between 

 the Mammalia and Birds, but is perfectly consonant with 

 Nature when the Tortoises are made immediately to fol- 

 low these last. In the first case there is an intervention 

 disagreeable to the eye and contrary to the opinion of 

 the naturalist, as well as of the ordinary observer ; in the 

 other there is only a chasm which the discoveries of a 

 future day may fully occupy. 1 rest therefore the general 

 accuracy of the above arrangement of the Annulosa much 

 less on the presence of every link in the chain of affinity, 

 than on this being uninterrupted by any thing known, 

 while it beautifully coincides with relations of analogy. 

 Still it is but a shadow, a pitiably faint shadow of the 

 truth. " Animadverli immensum opus Dei non posse 

 hominem assequi quamvis laboriosh quarat." And as it is- 

 an advantage to a person aware of his fault to be the first 

 to acknowledge it, I shall now show wherein I consider 

 the above observations to be most imperfect. 



• Aristotle describes their motion well : " vUotrai It *a.< vkrwx xu) ra 

 ivio* S* <wm *xp*m niouruv., *t zvpaiituti ry replf, *«< *p*£*r*i r» yti°<t 



2D 



