100 
PRE-CARBONIFEROUS FLOOR OF THE MIDLANDS. 
bite. In this case there is a local injection of the secretion 
into the tissues of the wound, and a local effect only is pro¬ 
duced. While the leech is sucking, this secretion bathes the 
wound, and being very diffusible it passes into the tissues 
around. When the leech drops off at the end of ten or 
fifteen minutes, the wound is literally soaked with the 
secretion, and the blood not only flows from the wound, but 
some of it will probably find its way into the tissues around 
its edges, so that the skin becomes blue just as if it had been 
bruised—■ (this is generally but not always seen). If you wish 
to stop a leech bite you must wash the wound well with water to 
wash away the secretion. 
To the leech, the possession of this secretion is essential 
for its existence. It thus obtains sufficient blood for its 
nourishment. A cut such as the leech can inflict would very 
soon stop bleeding, and the creature would at most obtain 
a few drops. But in addition the blood remains fluid within 
its body cavity. We know—many at least—by our own ex¬ 
perience how difficult it is to digest a milk-clot; for the 
coagulation of the milk within the stomach is perhaps the 
chief reason that it is to some a forbidden article of food. 
So with the leech ; it can easily assimilate the fluid blood, 
but its digestive juices would refuse to attack a solid blood-clot. 
THE PRE-CARBONIFEROUS FLOOR OF THE 
MIDLANDS. 
BY W. JEROME HARRISON, F.G.S. 
( Continued from pa ye 73.) 
5 .—The Silurians of Walsall .—Ten miles due west of 
Dosthill, the intervening space being occupied by the Trias, 
we find a considerable area of Upper Silurian beds lying 
around and east of Walsall. The lowest stratum exposed 
is the Upper Llandovery or May Hill Sandstone, which crops 
out near Hay Head and at Shustoke Lodge, two miles east 
of Walsall.* It is here very fossiliferous, and has a westerly 
dip. The rocks which lie below it are not visible, but if the 
fault which has brought the May Hill Sandstone to the 
surface had had but a little greater throw, we should, doubt¬ 
less, have found Cambrian or Pre-Cambrian rocks at the 
surface, for the entire thickness of the Lower Silurian strata 
is wanting in this part of South Staffordshire. 
* Jukes’ South Staffordshire Coalfield; Suney Memoir; p. 109. 
