ON AFFINITY AND ANALOGY. 305 



Art. X. — A few further Observations on Affinity and Analogy. 

 By J. O. Westwood, Esq., F.LS. 



Coinciding, as I iiilly do, in many of Mr, H. E. Strick- 

 land's observations on the distinction existing between 

 the affinities and analogies of organized beings, allow me a 

 few lines to correct the erroneous impression which his illus- 

 tration (pp. 224 and 225) of my remarks, is likely to cause, 

 and to remove the notion that they contain a fallacy. The 

 object of my short article was to record my opinion, — 



1. That relations of analogy and affinity are nothing else 

 than instances of more or less perfect resemblance : and 



2. That as these relations are absolutely comparative in 

 their nature, it follows that both kind of relations may co- 

 exist at the same time between any two animals, according 

 to the animals compared therewith. These opinions may be 

 thus illustrated : — 



1. The natural system depends not only upon the exist- 

 ence of a resemblance in essential peculiarities of structure, 

 or an agreement in the numerical majority of characteristics, 



, whereby the species of a genus, the genera of a family, the 

 families of an order, or the orders of a class, are linked to- 

 gether, whence the origin of affinity, but also upon less per- 

 fect resemblances, whereby a species of one genus is com- 

 pared with a species in some other genus, family, or order, or 

 a genus in one family is compared with a genus in some 

 other family, and so on, whence the origin of analogy. Both 

 these relations are, however, necessarily dependent upon re- 

 semblance^ and the approximations oi which Mr. Blyth speaks, 

 not only prove the occasional difficulty of drawing the line 

 between the two kinds of relations, but also the tmth of the 

 Linnaean adage " Natura non facit saltus," a principle which 

 Mr. Strickland would adopt in the lower groups, but reject 

 in the higher. 



2. The co-existence of these relations between any two 

 objects, is illustrated by the goat-sucker, bat, dragon-fly, and 

 Dioncua in the following manner. All these animals possess 

 inter se,\n their common character of fly-catchers, an analo- 

 gical relation ; but when I compare the two former, as verte- 

 brated animals, with the dragon-fly, as an invertebrated 

 animal, I find a higher relation (that is an affinity) existing 

 between the bat and the goat-sucker, than subsists between 

 either of these and the dragon-fly. When, however, I com- 

 pare these three animals with the plant, Dion(Ba, I find a re- 

 lation (that is an affinity) established between the dragon-fly 



