194; THE GEOLOGIST. 
19. Spirifera minima, Moore. Perfect enlarged exterior. 
20. . Exterior of the ventral valve. 
21. ' Terchratula (?) minuta, Moore. Perfect shell, enlarged exterior. 
22. ^ . Interior of dorsal valve. 
23. Rh.ynclionella (?) coronata, Moore. Enlarged dorsal aspect. 
24. . Interior, showing ventral aspect. 
25. . Exterior of ventral valve- 
FOREIGN CORRESPONDENCE. 
Lunar relations of JEarthquaJces. 
M. A. Pereey, in a paper read before the French Academy on the fre- 
quency of earthquakes during the latter half of the 18th century — rela- 
tively to the age of the nioon,and of the fi*equency of the phenomenon at 
the time of the moon crossing the meridian — furnishes a series of facts 
worthy of the highest consideration. Referring to his previous labours 
on this subject, he points out that, in the present paper, in contradis- 
tinction to his former method, if an earthquake has taken place on the 
same lunar day, in different pai'ts of the earth mthout the intermediate 
district being affected, that day is entered as many times as earth- 
quakes have taken place. In this way he has found that from 1801 
to 1850 the earth has trembled three thousand six hundred and fifty- 
five days, with a marked preponderance at the syzygies. 
If the mean lunation of 29'53 days be divided into eight equal 
parts the earthquakes will not be found to distribute themselves 
equally, but vrill show a preponderence at the beginning, the middle, 
and the end — the curves representing which will take a wave-Hke 
form, with two maxima and two minima. 
Uniting the numbers of the first and last eighths of the lunar 
month, the sum will express the monthly frequency at the new moon; 
the second and third combined give the frequency during the first 
quarter ; the fourth and fifth at the full moon ; while the sixth and 
seventh show the frequency at the last quarter. 
Again combining the results for the two syzygies and the two 
quadratures, we find that from 1751 to 1800 
Shocks of Earthquakes. 
At the Syzygies 1901-18 
At the Quadratures 1753'82 
Difference in favour of Syzygies 147'36 
After some furthei references to his preceding memoirs, M. Perrey 
proceeds — " One is then justified in admitting that earthquakes are 
more frequent at the syzygies than at the quadratures ; the conclusion 
we have arrived at from our researches of 1853 is now proved to be 
