After a march of six or eight hours, up the valley of the arroyo, through a heavy rain, and mud so deep that several of our horses gave out from exhaustion, we encamped in a circular bottom, near a deserted adobe house.  A caballada, of some 500 or 600 loose horses and mules is driven along with us, but many of them are miserable sore-backed skeletons, having been exhausted with hard usage and bad fare during the summer campaign.  Besides these, we have a large number of pack-mules, upon which all our baggage and provisions are transported.  Distance 10 miles.

We did not move on the 1st and 2d of December.  There being no cattle in the vicinity of our camp, a party was sent back to the mission, on the morning of the 1st, who in the afternoon returned, driving before them about 100 head, most of them in good condition.  After a sufficient number were slaughtered to supply the camp with meat for the day, the remainder were confined in a corral prepared for the purpose, to be driven along with us, and slaughtered from day to day.  The rain has continued, with short intermissions, since we commenced our march on the 30th of November.  The ground has become saturated with water, and the small branches are swollen into large streams.  Notwithstanding these discomforts, the men are in good spirits, and enjoy themselves in singing, telling stories, and playing monte.

December 3.—­The rain ceased falling about 8 o’clock this morning; and, the clouds breaking away, the sun cheered us once more with his pleasant beams.  The battalion was formed into a hollow square, and, the order of the day being read, we resumed our march.  Our progress, through the deep mud, was very slow.  The horses were constantly giving out, and many were left behind.  The young and tender grass upon which they feed affords but little nourishment, and hard labour soon exhausts them.  We encamped on a low bluff, near the arroyo, timbered with evergreen oak.  Distance 8 miles.

December 4.—­I was ordered with a small party in advance this morning.  Proceeding up the valley a few miles, we left it, crossing several steep hills sparsely timbered with oak, from which we descended into another small valley, down which we continued to the point of its termination, near some narrow and difficult mountain gorges.  In exploring the gorges, we discovered the trail of a party of Californians, which had passed south several days before us, and found a horse which they had left in their march.  This, doubtless, was a portion of the party which captured Mr. Larkin, and had the engagement between Monterey and St. Juan, on the 17th ult.  The main body coming up, we encamped at three o’clock.  The old grass around our camp is abundant; but having been so much washed by the rains, and consequently exhausted of its nutritious qualities, the animals refused to eat it.  The country over which we have travelled to-day, and as far as I can see, is mountainous and broken, little of it being adapted to other agricultural purposes than grazing.