41(> Remarks on Zoological Classification. 



contain subdivisions, distinguished from each other by a suc- 

 cessive leaning towards developement in the direction of the 

 same elementary structures, nor need there be any limit to the 

 downward operation of such a principle. On the other hand, 

 I do not see any reason whatsoever for expecting that in each 

 sub-division, and in each department of such sub-division, the 

 same order should be always followed, and that the force of 

 developement should always fall in one unvarying succession 

 upon each of the supposed elementary structures. 



10. This research confirms many analogies suggested by 

 ingenious writers, such as those between Bivalves and Dip- 

 tera, and between Arachnida and certain Radiata. An es- 

 tablished linear series checked by a parallel series would by 

 gradual progress and comparison of structure, settle many 

 such doubtful points of organization and function. The Ta- 

 ble also confirms the suggestion of a late writer, as to the zoo- 

 logical series passing in opposite directions from the Simiada. 



11. The botanical arrangement is exceedingly more diffi- 

 cult than the zoological. Though in Botany some kind of 

 approach has been made towards definite limits of families, a 

 work most imperfectly performed in Zoology ; yet on the o- 

 ther hand, in Botany no great recognized natural groups were 

 to be found till very lately, beyond the Cryptogamous, Mono- 

 petalous, and Endogenous structures, so that families had to 

 be separately weighed from every possible quarter. In Zoo- 

 logy, the leading structures are much more distinctly marked, 

 except perhaps in the Aves and Pisces, and even these have, 

 in some degree, passed satisfactorily through the hands of 

 Swainson and Cuvier. 



12. The limits of the alliances are not always very definite, 

 and some of them may hereafter require consolidation or sub- 

 division. I have endeavoured to use, as a sort of scale, some 

 obvious natural assemblages, apparently of this sort, such as 

 the Pachydermata, Ruminantia, Raptores, Natatores, Gral- 

 latores, Chondropterygii, Malacopterygii, Abdominales, My- 

 riopoda, Orthoptera, Neuroptera, Lepidoptera, and Echino- 

 dermata. I have also been aided by the presumed parallel- 

 ism of the alliances at equal distances from the extremities of 

 the series ; without such reference to the Crustaceous allian- 

 ces, it would scarcely have been possible to surmise the com- 

 parative rank of the groups in the Insecta, and the matter will 

 after all require steady re-examination. 



13. The want of some such work as Dr. Lindley's Natural 

 System, puts me under a difficulty in indicating the limits of 



