THE MORPHOLOGICAL COMPOSITION OF ANIMALS. H5 



in general and the Annelids. For if that masking of the 

 individualities of the segments which we find distinguishes 

 the higher forms from the lower, has been going on from the 

 beginning, as we may fairly assume; it is to be inferred that 

 the individualities of the segments in the lower forms, were 

 originally more marked than they now are. Eeversing those 

 processes of change by which the most developed Annulosa 

 have arisen from the least developed; and applying in 

 thought this reversed process to the least developed, as they 

 were described in the last Chapter; we are brought to the 

 conception of attached segments that are all completely alike, 

 and have their individualities in no appreciable degree sub- 

 ordinated to that of the chain they compose. From which 

 there ' is but one step to the conception of gemmiparously- 

 produced individuals which severally part one from another 

 as soon as they are formed. 



209. We must now return to a junction whence we 

 diverged some time ago. As before explained under the 

 head of Classification, organisms do not admit of uni-serial 

 arrangement, either in general or in detail; but everywhere 

 form groups within groups. Hence, having traced the phases 

 of morphological composition up to the highest forms in any 

 sub-kingdom, we find ourselves at the extremity of a great 

 branch, from which there is no access to another great branch, 

 except by going back to some place of bifurcation low down 

 in the tree. 



There exist such similarities of shape" and structure be- 

 tween the larval forms of low Molluscs and those of Annelids 

 and Rotifers, as to show that there was an early type common 

 to them all; and its probable characters, suggested by com- 

 parison, seem to imply that it had arisen from some coelen- 

 terate type, intermediate between the Cnidaria and the Cteno- 

 phora. But there is this noteworthy difference between the 

 molluscan larva and the allied larvae, that it gives origin to 

 only one animal and not to a group of animals, united or 



