ON MINERAL VEINS IN CARBONIFEROUS LIMESTONE. 429 
As opportunity offered I had been giving an examination to the Carboni- 
ferous-Limestone veins of the North of England, in some of which I also 
detected the presence of a freshwater fauna. 
During the past year I have been almost daily occupied in an examination 
of 134 different samples, derived from the lead-mines of Cumberland and 
Yorkshire. 
The process necessary for the discovery of organic remains is often difficult, 
and needs much perseverance, a single sample occasionally requiring several 
days’ examination. 
The samples selected are from the less mineralized portions of the veins, 
consisting generally of the “ Dowks” or clays. They have therefore to be 
dissolved and washed, which, from the intractable nature of the material, is 
often a difficult operation; and the residue is then examined. 
From the difficulty involved in a continued examination of many minute 
organisms, the time has not been sufficient to enable me now to give a detailed 
account of my investigations, which I propose doing on another occasion ; 
but I proceed to give the general results. 
Out of the 134 samples I have examined during the past year, I have 
found organic remains more or less abundantly in not less than exghty—a fact 
sufficient to show that, as a general rule, they may be found in almost every 
vein, if a careful examination be given to its contents. 
From the investigation of the remains I have obtained from the Cumber- 
land and Yorkshire veins, it is difficult at present to arrive at any precise 
conclusion (as in the case of the Somersetshire and South-Wales mines) as 
to when the veins were formed, with the exception perhaps of the Fallow- 
field Mine in the Tyneside district: all the samples of “‘dowk” from this 
mine have very much the character of coal-shales ; and from the very interest- 
ing fact that I have found specimens of a seed (Flemingites gracilis, Carr.) 
which belongs to the Coal-measures in this mine, there is every reason for 
fixing the infilling of this vein at the age of the Coal-measures. This mine 
also yields Valvata and Bythinia, freshwater univalyes, and a bivalve closely 
related to Pisidiwm. 
Amongst the organic remains the chief interest will attach to the presence 
of Valvata and other freshwater shells, often in considerable abundance and in 
districts wide asunder, showing most conclusively, as I have already pointed 
out on the Mendips, a connexion between the North-of-England mines and 
bodies of fresh water, which must have found their way into the veins from 
some neighbouring land area. 
Of vertebrata I have obtained teeth and scales of Petalodus, Ctenoptychius, 
Squaloraia?, Sauricthys?, Hybodus?, Acrodus? Brachiopoda are represented 
by Zellania, Thecidium, Spirifer, Rhynchonella, Terebratula, and Discina. 
Foraminifera are generally very rare, and in many veins not to be traced. 
In the Keld-Head mines, however, they are most abundant, especially a 
Nummuline-like form. Altogether, I have obtained five or six genera, in- 
eluding the above and Nodosaria, Cristellaria, Dentalina, Rotalina, and also 
egg-like bodies like single cells of Nodosaria or Dentalina. 
Entomostraca of several species are very widespread, and are probably the 
most constant organisms, if Encrinital stems are excepted, which are very 
_ generally obtained. 
