XXX PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 
present in the atmosphere, but we do know that the deposits of the 
time covered ground now high elevated above the sea. Patches of 
these now alone remain scattered at various distances from each 
other, and attest the denudation which the whole deposit has suffered 
in such situations from the combined action of atmospheric influences 
and of breakers wasting away the lands as they gradually rose above 
the sea, and indeed, in some cases, during many a rise and depression 
producing changes in the relative level of sea and land. 
Regarding paleontology we have received several communications. 
The first paper read was from Mr. Salter on the structure of 
Trinucleus, with remarks on the species, in which the author, after 
adverting to the name as that of Llwyd, given so far back as 1698, 
and revived by Sir Roderick Murchison, describes this genus, the 
individuals composing the species of which are so abundant in the 
Silurian rocks, especially in the lower division of them. Mr. Salter 
more particularly points out the peculiar perforate border as a highly 
interesting part of these animals. It would be difficult to explain 
the author’s description without the aid of his figures, but he endea- 
vours to show that the punctate or plicated fringes are only modifi- 
cations of each other, adding that these perforate or spinous fringes 
are not essential, but only supplementary parts of the head; the 
width of the head, without the fringe, being exactly that of the body ; 
so that when the animal is doubled up, the frmge projects freely on 
all sides. Mr. Salter then proceeds to consider a subject of much 
importance, especially when the Trilobites of different and distant 
localities are under consideration, namely the identity or distmetness 
of Trinuclei referred, or to be referred to the species 7. Caractaci 
(Murchison). From the examination of specimens, he considers that 
Trinucleus ornatus of Sternberg, T. tessellatus and T. Bigsbii of 
Green, 7. Caractact of Murchison, 7. elongatus and T. latus of 
Portlock, and T. Goldfussi of Barrande, are all the same species, for 
which he would preserve the name of Trinucleus ornatus, that having 
been first given by Sternberg. Of this species four distinct varieties 
are admitted :—1. Sternbergii (Salter) ; 2. Caractaci (Murchison) ; 
3. elongatus (Portlock) ; 4. favus (Salter). Five species of the genus 
Trinucleus are known to Mr. Salter, namely 7. ornatus, Sternberg, 
T. seticornis, Hisinger, T. granulatus, Wahlenberg, T. fimbriatus, 
Murchison, and 7. radiatus, Murchison. 
Mr. Lyell in his paper on the coal-field of Eastern Virginia has 
figured certain bivalves found in the carbonaceous shales associated 
with the main coal seam. They are discovered in multitudes, 
dividing the shale into thin laminz like plates of mica, and resemble 
Posidonomya, and more than any other P. minuta. THealso figures 
and describes, chiefly from notes supplied by Prof. Agassiz and Sir 
Philip Egerton, ichthyolites obtained from the same coal-field. These 
consist of Dictyopyge macrura (Catopterus macrurus of Redfield), 
the most abundant species ; a second species of Dictyopyge, and a 
Tetragonolepis. 
Our Foreign Secretary, Mr. C. Bunbury, has given us detailed 
descriptions of fossil plants from the same coal-field, and brought to 
