4-08 SYSTEM OF INSECTS. 



pears to prevail most widely in nature is what may be 

 called the quaterno-qidnary ; according to which, groups 

 consist of four minor ones ; one of which is excessively 

 capacious in comparison of the other three, and is al- 

 ways divisible into two ; which gives Jive of the same 

 degree, but of which, two have a greater affinity to each 

 other than they have tothe other three*. Mr. W. S. 

 MacLeay, in the progress of his inquiries to ascertain 

 the station of Scarabceus sacer, discovered that the thale- 

 rophagous and saprophagous Petalocerous beetles re- 

 solved themselves each into a circle containingjfe such 

 groups. And having got this principle, and finding that 

 this number and its multiples prevailed much in nature, 

 he next applied it to the Animal Kingdom in general : 

 and from the result of this investigation, it appeared to 

 him that it was nearly, if not altogether, universal 5 . 

 Nearly at the same time a discovery almost parallel was 

 made and recorded by three eminent Botanists, MM. 

 Decandolle, Agardh, and Fries, with regard to some 

 groups of the Vegetable Kingdom c ; and more recently 

 Mr. Vigors thinks he has discovered the same qui- 

 nary arrangement in various groups of birds d . This is 



least he has not built his system on this foundation, which appears 

 an essential part of the quinary arrangement. (See Mr. W. S. Mac- 

 Leay in Linn. Trans, xiv. 56 .) As to value, the PapilionidcB con- 

 stitute the typical group or centre of the Order, though the PhalfE- 

 nidcs prevail as to numbers : but neither of these are resolvable into 

 two primary groups. 



a Linn. Trans, xiv. 56. It is to be observed, however, that 

 what Mr.. MacLeay calls the aberrant groups are usually also resolv- 

 able into two. b Hor> Entomolog. 318, et passim. 



c Linn. Trans, ubi supr. Mr. W. S. MacLeay informs me that 

 M. Agardh has found that the distribution of Fu-ci is regulated by 

 the same law. * Zool. Jouni. iii. 312 . 



