162 KANSAS CITY REVIEW OF SCIENCE. 
laws of mental development obtain whether one’s capacity be remarkable or in- 
ferior. 
Such are the fundamental principles of mental development as I conceive 
them, and as such are they slowly coming into favor among those who strive to 
know the kind and direction of that current which forms the substratum of all 
our mental process. In conclusion, I know of no better instruction which will 
induce students to continue in improvement after graduation; none which will 
so much inspire the teacher to grow, after being well seated in his professional 
chair. Such teaching will best enable a person to withhold the expression of an 
opinion when he has none worth expressing; to rely somewhat upon his own ob- 
servation and judgment of men and things rather than upon some ‘‘ authority,” 
to form proportionate judgments when complete ones are impossible; to reserve 
judgments wholly when we have not heard both sides of a controversy; to stand 
aloof from-the acceptation of any views whose details, bearings and history have 
not been faithfully examined; to feel security in honest convictions when formed 
upon the broadest foundation within the range of the individual; to rise and re- 
solve anew when misfortunes beset us, instead of weakening under a flood of 
tears; to unconditionally defend his right to reject or reserve judgment upon 
any beliefs which may be presented for his consideration if their data contradict 
the experiences of his short life time. 
GCEOLOGGAND: MIN EN Ac@ Ge 
GEOLOGY AND EVOLUTION. 
BY THE LATE PROF. B. F. MUDGE. 
CHAPTER I1.—RADIATES. 
The radiates are the lowest (excepting Protozoa), of the five great sub- 
kingdoms of animals. They do not appear with the first traces of life in the 
Lower Silurian, though they are found soon afterwards. Two of the higher 
sub-kingdoms, the Mollusks and Articulates, appear in the Acadian and 
the Radiates not till the Potsdam. It is also a well settled fact that the lowest of 
the Radiates are not the first representatives of that sub-kingdom. Acalephs and 
Echinoderms appear at the opening of the Primoid, or first division of the Lower 
Silurian and Polyps, at the close of the Trenton, or after a period of one-fifteenth 
of the earth’s geological history. Dana says: ‘‘If we may trust the records, 
Echinoderms or the highest type of Radiates were represented by species 
(Crystids and Crinids) long before the inferior type of Polyps existed; this can 
hardly be accounted for satisfactorily on the supposition that the earliest Polyps 
