228 VINE: CARBONIFEROUS ENTOMOSTRACA, ETC. 
species have been considerably enlarged by the discoveries of Mr. 
John Young, of the Hunterian Museum, Glasgow, and members of 
the Scotch Geological Survey . Very few, however, of the Carbonif- 
erous species range from the Silurian strata of this country. There 
is, therefore, very little difference in the generic character of the 
Permian and Carboniferous fauna of this type, but there is a consid- 
erable difference in the genera of the Carboniferous and of the 
Silurian eras. In the Silurian ages Beyrichia , Primitia and Leper- 
ditia , had a most extensive range, and there were a larger number 
of species of all the genera, but Kirkbya is very rare in the Silurian 
rocks. In the Carboniferous rocks these generic characteristics 
were reversed ; KirJcbya were abundant, Beyrichia not so abundant 
in specific character, Primitia almost unknown, and Leperditia like- 
wise few in number. It is impossible to make an exact comparison, 
because all the fossils being minute and difficult to identify, except 
by those who give to their investigations a patient earnestness, 
which is, alas, far from common in our matter-of-fact age. The 
present paper must not be looked upon then, as the work of a 
specialist, or in any way exhaustive. It may be possible that 
specialists will detect errors in the descriptions and identifications of 
the species enumerated below, but as these know full-well the 
difficulties that have to be encountered in work of this sort, I fear 
their criticism less than the frown of others, who have never yet 
attempted special labours. I feel certain that there are earnest 
youths in some of our Yorkshire Geological and Microscopical 
Societies, who are looking out for labour of some sort in the field, 
and ultimately in their homes. If there be such, I recommend to 
them the searching for, and then the systematic study of the more 
minute organic forms of our Yorkshire shales, and I feel confident 
that they will be amply rewarded in their researches. It is in the 
interest of these more especially that I write this paper, at the same 
time, I do not undervalue the work of the specialist, and I have 
identified to the best of my ability, and have given such descriptions 
of the species found in the shales as shall merit some approval of 
my labour even from them. I may say that in comparing my 
Yorkshire specimens, though I have been careful to look up the text 
