SCIENTIFIC SUMMARY. 
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those found in the Old-Red-Sandstone rocks in Caithness, Orkney, and Shet- 
land, from which it was inferred that the quartzites and shales in which the 
fossils are imbedded must he classed with this formation. The authors also 
described the great series of contemporaneous and intrusive igneous rocks of 
Old-Red-Sandstone age, adducing evidence in proof of the great denudation 
which has taken place in the members of this formation in Shetland. 
A Silurian Area near Cardiff . — Mr. Sollas described to the Geological 
Society, on April 9, the occurrence of unmistakable Silurian rocks about 
Rhymney and Pen-y-lan, near Cardiff. They comprise beds belonging to the 
Wenlock and Ludlow groups, and pass conformably upwards into the Old 
Red Sandstone. The district affords a good base for a measurement of the 
thickness of the Old Red Sandstone on the south of the South Wales coal- 
field. This was found to he a little over 4,000 feet. The thinning out of 
the Old Red Sandstone and Silurian strata, together with the marked change 
which takes place correspondingly in the lithological characters of the latter 
formation on passing from the north to the south side of the coalfield were 
taken to indicate an approach to a shore-line. This shore-line belonged to 
land which, as shown by the great thickness of the Devonian beds, could not 
have extended far south. It corresponded to Mr. Etheridge’s barrier between 
the Old Red Sandstone and Devonian seas. The sandstones with Old-Red 
characters, such as the Hangman Grit and the Pickwell-down Sandstones, 
occurring in the Devonian formation, were deposited at intervals when this 
barrier was submerged to a greater depth than usual. The Cornstones were 
stated to thin out to the south along with the other sedimentary beds of the 
Old Red Sandstone, and were regarded as derived from the denudation of 
previously upheaved limestones, such as the Bala and Hirnant. The paper 
concluded with a description of the characters of the more interesting rocks 
and fossils. 
Were Ichthyosaurs Viviparous t — Professor H. G. Seeley laid before the 
Geological Society at its last meeting the evidence which seemed to him to 
show that certain species of Ichthyosaurus might possibly have produced 
living young. He described several specimens in which the remains of one 
or more small individuals have been preserved within the body-cavity of 
larger ones. One of these was described and figured in 1822, by Jager ; a 
notice of another was published in 1846 by Dr. Chaning-Pearce, who 
suggested that it furnished evidence in favour of the viviparity of the 
Ichthyosaurs. Other examples are preserved in museums in Germany, and 
one in Madrid, and most of them have been examined by the author, who 
adduces the state of preservation of the small individuals, in contrast with 
that of the traces of fish and Cephalopoda, the remains of food, which are 
found in the stomachal region of the larger individuals, in advance of the 
position occupied by the smaller ones, as a proof that we have not here to 
do with a case of cannibalism. The position of the smaller skeletons with 
the head generally turned towards the pelvic region of the larger ones is 
also regarded as indicative of their standing in the relation of parent and 
offspring. As some of the young specimens possess limbs it would seem 
that the supposition that the Ichthyosaurus passed through a sort of tadpole 
stage is erroneous. It must be observed, however, that, as we are entitled 
a priori to assume that the Ichthyosaurs, if they produced living young, were 
NEW SERIES, YOL. III. — NO. XI. Y 
