SYSTEMATIC ZOOLOGY—GILL. 467 
tended for five. Exactly what the philosophers thought they meant, 
or what strange visions they may have conjured up may never be 
known. ' But for a time (1822-1842) the school of quinarians, as 
they were called, claimed most of the naturalists of Britain. The 
most zealous of the school (William Swainson) was especially dis- 
pleased with the developmental hypothesis of Lamarck and charac- 
terized the “speculations ” of the great Frenchman “ not merely as 
fanciful, but absolutely absurd.” 
But it was the much-contemned hypothesis of descent with modi- 
fications that was destined at last to relieve biological science of the 
wild and irrational speculations and classifications of the nature- 
philosophers, physiophilosophers, circularians, quinarians, trinarians, 
septenarians, and their like that flourished during the first half of 
the past century. 
DEVELOPMENT THEORY. 
Although there had been previous indications of belief that trans- 
mutation of species might have been a cause for the diversity of 
animal life, Jean Baptiste Pierre Antoine de Monet de Lamarck 
(1809) first framed a hypothesis that had a logical basis, although 
weakened by unproved postulates. In view of those weaknesses, it 
was easy to bring forth many facts that seemed to militate unanswer- 
ably against it, and such were well put forward by Cuvier; as the 
hypothesis, too, was very unpopular, it was for a long time stifled. 
In the meanwhile geological and paleontological investigation, com- 
parative morphology, physiology, embryology, and zoogeography, as 
well as systematic zoology, were revealing innumerable facts that 
pointed all in the same direction and were only explicable collectively 
by the assumption that they were the result of original community 
of origin and subsequent deviation by gradual changes from time to 
time. The facts were at length collocated with extreme skill by 
Charles Darwin (1859) and a rational explanation of their evolution 
by means of natural selection made the new development theory ac- 
ceptable to well-informed naturalists and logical thinkers generally. 
SEQUENCE OF GROUPS. 
It had been almost the universal custom from olden time, as well 
as during the Linnean era, to commence the enumeration or cata- 
logues of animals with the forms exhibiting most analogy with man 
and consequently the highest in the scale of organic nature. As long 
as species were assumed to be individually created this was perhaps 
the most natural course, and at least had the advantage of proceed- 
ing from the comparatively known to the almost unknown. A sig- 
nificant and noteworthy exception to this mode of procedure among 
