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CONTRIBUTIONS TO THE HISTORY OF THE 
ROTIFERA, OR WHEEL-ANIMALCULES. 
BY PHILIP HENRY GOSSE, F.R.S. 
PART IV. - 
THE FLEXIBLE CREEPERS (nOTOMMATINA) . 
U NINITIATED persons are sometimes startled, and not a 
little stumbled, by reading in books of scientific natural 
bistory sucb statements as this : “A b is a mucb more 
perfect form tban C cl .” Tbey pause and ask wbetber 
there can be any degrees of perfection in the handiwork of 
the All-wise and Almighty Cod. Are not all His works 
perfect ? The answer must be that they are ; understanding 
the term to express the adaptation of the creature, and of all 
parts of its organization, to the purposes for which they were 
designed. 
The naturalist, however, does not mean this. He is not 
speaking of the organism as an individual, with reference to 
its own objects and requirements ; but as one of a series, with 
reference to an ideal standard of aggregate qualities presented 
by that series. Thus, when we consider Birds, we have before 
us a vast assemblage of creatures, the most prominent and 
characteristic feature of which is that they are constituted for 
flight, by means of a peculiar development and arrangement 
of tegumentary organs (feathers), associated with peculiar 
developments and arrangements of the skeleton, muscles, 
and breathing organs. Thus, then, we acquire a definite 
idea of a bird, notwithstanding that this idea is presented 
under considerable diversity in all these details, when we 
examine the thousands of species that are known ; nor does 
this diversity at all interfere with the unity of the model 
or pattern which is involved in the aggregate idea of a 
bird. The comparison of these details, however, soon shows 
us that the characteristic features of a bird are much more 
prominent in some species than in others. In the humming- 
bird, the frigate-bird, or the swift — in the great breast-bone, 
the enormous lungs and chains of air-cells, the hard, dense, 
thick pectoral muscles, the firm rigid feathers, drawn out to 
