SCIENTIFIC SUMMARY. 
organic origin. With these he also observed several isolated markings 
which appeared to be more regular in shape than the fragments of the 
vegetable remains usually are, and to bear some resemblance to fish-scales. 
From this quarry he afterwards obtained some fish remains, and amongst 
them the palatal tooth of a species of Psammodus , probably P. porosus. 
The following fossils were identified : Sagenaria Weltheimiana, Cucullcea 
Grijfithice, Avicula Damnoniensis , and Orthis crenistria. — Vide Dublin 
Quarterly Journal , April, 1864. 
The Irish Crannoges. — Mr. G. Henry Kinahan has minutely explored 
these forms of prehistoric dwellings, and given a great deal of minute 
detail as to their form and mode of construction. After having described 
various implements, &c. discovered in the vicinity of the crannoges, Mr. 
Kinahan concludes — 1st. That iron was in use in the early age of the 
crannoges. This is proved by the presence of knives, but the sharp points 
on the stakes would lead to the same conclusion ; also the number of 
bones which must have been used for the sharpening of metal instruments. 
The cuts which were observed on pieces of deer’s horn must have been 
made with a very fine saw, as there are no marks of graining on the 
surface. 2nd. That when the crannoges were first built, the surface of 
the lake (Lough Rea) must have been at least seven feet lower than at 
present, as is proved by several sections, and by the old turf-banks at the 
south-east end of the lake, over which there are five or six feet of water. 
3rd. That at a subsequent period the western part of the lake must have 
been twelve feet deeper than at present ; this being proved by the fact that 
there are at least six feet of shell-marl beneath the artificial works. The 
change in the level of the lake must, in the author’s opinion, have been 
caused by the silting-up of its outlet. The ancient stream from the lake 
seems to have been at the west end of the town, as in that place there is 
an alluvial deposit, while at its present outlet there is a strong corn-gravel ; 
and a little below its present bed there seems to be rock. It is well 
known that the silting-up of a lake is a very tedious process. First, the 
weeds grow during the summer, and catch the heavy particles that 
are coming out with the water ; but in the winter-floods all the weeds are 
broken down, and most of the accumulated matter is carried away ; so 
that in a century it would hardly raise the bottom of the stream more than 
six inches, which would make the crannoges to have been built about 
1,400 years before the lake reached its present level. But it must be 
remembered, that since the town of Loughrea was built the lake could 
scarcely have changed its level ; for the eastern outlet ran at the foot of 
the town- wall, and the inhabitants would have kept it open, being part of 
the defences of their town. Loughrea is more than 400 years old, and 
hence the conclusion is arrived at, that the crannoges are of pre-Christian 
origin. — Vide Transactions of the Royal Irish Academy for 1863. 
Minute Geologic Evidence. — Mr. Edward Blytli has recently pointed out 
the existence of two very distinct forms of deposit, which are occasionally 
found on the teeth of fossil herbivora. By an examination of these the 
geologist is, to some extent, enabled to determine whether an animal lias 
been in the wild or domesticated condition. “There is a small particular 
or character which generally distinguishes a wild herbivorous animal from 
a tame one ; and this is, a certain incrustation of brown tartar upon the 
