THE PRIMARY TYPES OF FORM. 103 



between each and all of such as we may select for this 

 purpose, the circular affinities of the whole will be 

 sufficiently established by anology ; whether we are ac- 

 quainted, or not, with the precise links that connect the 

 several portions. Our main object, however, is to 

 adduce further proofs of the proposition contained in 

 our early volume of this series, namely, that all animals 

 could be referred to certain primary types of form. It will 

 therefore be advisable, in this place, briefly to recapitu- 

 late what was then said, that the naturalist may judge 

 how far the characters there given accord with those by 

 which we have defined the primary types of fishes. 



(92.) In the first place, we have said that the most 

 perfectly typical individuals of every natural group 

 are those which exhibit the highest development of 

 those characters by which the group, as a whole, is 

 distinguished ; or, in other words, Ci they are endowed 

 with the greatest number of perfections, and capable of 

 performing to the greatest extent the functions which 

 peculiarly characterise their respective circles." This 

 pre-eminent perfection shows itself, also, in nearly all 

 such types as are of this primary rank. l( This is 

 apparent in the order Quadrumana among beasts, and 

 in that of Insessores among birds;" both of which are 

 the most perfect, and by far the largest, groups in their 

 respective circles. Among the Annulosa, again, the 

 Ptilota, or winged insects, are probably ten times more 

 numerous than all other annulose groups put together. 

 In tracing this peculiarity in the typical groups of 

 lower divisions, we find it also very prevalent ; and even 

 in looking to sub-families, or even genera, we find that 

 the genus Picus, Sylvicola, Sylvia, among birds, and 

 that of the restricted sub-genus Scarabceus (MacL.) 

 among insects, are all remarkably abundant in indi- 

 viduals, when compared with the remaining contents of 

 their respective circles." Every ichthyologist will per- 

 ceive that the foregoing observations are as applicable 

 to the order of Acanthopteryges among fish, as if 

 they had been expressly written to distinguish them 



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