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proportions in the masses, but the crystals may be a double salt, 
composed of one equivalent of sulphate of soda, and one equiv- 
alent of sulphate of magnesia; each retaining an equivalent of 
water. In the masses, the closest approximation is 42 parts of 
sulphate of magnesia found, instead of 46 parts required. 
'The communieation of Mr. Bishop embraces interesting facts. 
'These saline deserts cover extended areas, in different parts of 
South America, and, so far as he has been able to learn, the 
saline matter differs in kind at the different points. The ten- 
dency of saline matter contained in any soil is to rise through 
the aid of moisture to the surface, where, the water escaping, the 
salt is deposited. This effect, contrary to the gravitating influ- 
ence, is the most common cause of deserts, and may be exerted 
everywhere, when the evaporation of water from a given surface 
becomes much greater in amount than that surface receives in 
the form of rain and dew. The cultivation of saline deserts by 
washing down the saline matter, exhibits the opposite action of 
water in restoring fertility, and it is by no means essential that 
the water should contain organic matter to insure the full effect, 
as the soil of deserts generally contains all the organic matter 
of many years’ accumulation. 
Dr. Wyman made a few remarks on some of the 
habits of the painted tortoise (Emys picta) during the 
breeding season, which he had recently observed. 
Dr. Wyman also gave some account of the develop- 
ment of the dorsal cord in the Alewive, (Alosa vernalis.) 
The dorsal cord has been generally described as terminating 
anteriorly between the auditory capsules, and, in consequence 1t 
has been inferred that the true vertebral column does not exte 
beyond the basilar portion of the occiput; and that the occiput 
is the only part of the cranium which has a vertebral structure- 
In the Alewive, he had seen the dorsal cord, in the earlier 
specimens, uniformly extending as far forwards as the space 
between the eyes, and consequently into the region of the ah- — — 
terior sphenoid ; subsequently, as the face is enlarged, the anono, 
part of the cranium seems to be carried forwards, and then n a 
