SCIENTIFIC SUMMARY. 
115 
by human teratology. There is frequently found an incurvation of the 
vertebral column of man, at the level of the second or third dorsal vertebrae, 
yet in no case is there a true articulation produced. In ten cases of 
lumbar incurvation which the author observed, not one presented the least 
approach to a ginglymoid articulation. Again, M. Serres writes : — If we 
suppose this joint of the glyptodons to have been produced artificially, it 
could never have descended from one generation to another, for we find 
that when in man an entirely new hip-joint is produced (as in scrofulous 
affections, when the head of the femur is luxated, and develops an artificial 
cotyloid cavity) the new form is wholly individual, and is never trans- 
mitted to succeeding generations. The author then draws the conclusion 
that the vertebro-sternal articulation in the glyptodon was created with 
the animal itself. 
Relation of the Aymestry Limestoneto the Lower Ludlow. — In the last number 
of the Geological Society’s “ Journal” a short communication appears on this 
question. Mr. R. Lightbody, who has prepared a section of the Aymestry 
limestone at Mocktree, and who has evidently paid considerable attention 
to the subject, proposes that the term Aymestry limestone, as a division , be 
discontinued, for the following reasons : — ( a ) There is a constant intercala- 
tion of calcareous beds from the top of the Aymestry limestone to the 
bottom of the lower Ludlow, (b) A large proportion of the Aymestry 
limestone fossils are identical with those of the lower Ludlow, (c) The 
lower Ludlow star-fish are found above the whole thickness of the 
Aymestry workable limestone, {d) It is impossible to say exactly where 
the one formation begins and the other ends, (e) The Aymestry, or thick 
limestone, does not exist through large tracks of the Ludlow rocks, but 
only where certain fossils are very abundant. 
MECHANICS. 
The Suez Canal. — Mr. Hawkshaw, at the instance of the Egyptian 
Government, has examined the works in progress for the construction of 
the great intermarine ship canal at Suez ; and in an elaborate report, 
favourable to the enterprise, gives reasons for reversing the verdict of 
impracticability pronounced by Mr. Stephenson and other engineers, and 
generally accepted in this country. The fact was ascertained, in a survey 
undertaken by the advice of Mr. Stephenson, that there was no absolute 
difference in the mean levels of the Red Sea and the Mediterranean, and 
he thence concluded that the canal would have no current, and would, in 
course of time, become stagnant and silt up. He also supposed that the 
entrance to the canal at Port Said could not be kept open by any reason- 
able expenditure of money, in consequence of a drifting of sediment, 
brought down by the Damietta branch of the Nile eastwards along the 
coast. There is now no doubt that these inferences were crude and hasty. 
Mr. Hawkshaw shows that the difference in the rise of the tides in the 
two seas (viz., for equinoctial spring-tides, 3’67 feet at Suez, and only 
0’42 feet at Port Said), would cause an alternating current which may 
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