The extension of sheep husbandry which is going on in the United States, and the importance of his services therein, bid fair to place the Shepherd's dog very soon in the front rank for real utility in the public estimation. It may, in fact, be affirmed that this branch of rural industry cannot be pursued with complete success without his aid - especially in all that part of our country, to wit: the mountain ranges, from Maryland to Georgia, which nature may be said to have designed for our national sheep pastures, and which must be so appropriated, when their peculiar advantages for that important object shall have gotten to be more generally understood.

Of this breed of dogs there are several varieties, few specimens of which have been imported. The Pyre-nean, or St. Bernard's dog, is one of great size, immense strength, and indomitable courage. He accompanies the large merino flocks of Spain in their annual migrations to the mountains, protecting them from the numerous wolves with which the Pyrenees abound. Two individuals (unfortunately both males), splendid specimens of that breed, were sent to the writer of these sketches by that spotless patriot, and illustrious friend of our country, General Lafayette; recommended by him, from personal experience, as being of inestimable value to wool-growers in all regions exposed to the depredations of wolves and sheep-killing dogs. With a view to this agricultural necessity of our country, the author of this work has ventured to put in requisition, for the procurement of another pair, the kind offices of G. W. Lafayette, who, with all his other virtues and purity of character, inherits, also, in all its force, his honoured father's devoted and generous attachment to America.

The Pyrenean, or St Bernard dogs, sent by General Lafayette, were white, with a large portion of light brown colour. There are said to be two breeds of the Pyrenean, as well as of the Newfoundland: - one with longer, the other with shorter hair. Both are trained, in the winter time, to "carry a basket with some food and wine; and thus equipped, they sally forth from the Hospice of St. Bernard's, and other passes, in search of travellers who may have lost their way, or fallen beneath the snows of the preceding night They are followed by the monks devoted to that service 6f humanity; and, every winter, several lives are saved by their united means."

But the true shepherd's dog, most in use, and best adapted to the common care of sheep, and all the duties connected with that business - except that of protection from wolves - is a much smaller animal, seldom two feet high. From General Lafayette, on another occasion, we received a pair that were perfectly black; with head and nose sharp and pointed, and with a manner and countenance indicating uncommon alertness and intelligence. They were placed the day of their arrival, for safe keeping, in a kennel at Green Mount, near Baltimore; escaped the same day, and, though advertised, with all the notable circumstances of their importation, were never recovered. In Great Britain, and particularly in Scotland, the colours of the shepherd's dog are more mixed with shades of red and brown; or black dogs, with sharp ears, turning down at the tips. The Scotch breed is, probably, the one best suited to our purpose, where there are no wolves; and where there are, it should be accompanied by the large dog of the St. Bernard's breed, whose instinct prompts him, as we learn from a gentleman who has had good opportunities to judge, to remain constantly, both night and day, with the sheep; and whether the master be present or not, they always remain on duty; and the shepherd, with the utmost confidence, leaves them, for many hours together, in sole custody of the flock. At such times, woe be to the prowling wolf, or sneaking dog, that comes in their way. He is torn to pieces with the utmost ferocity. With man he is more gentle, though he, if a stranger, is not permitted to get within reach of their charge.

The sheep dog, in natural power of intellect, is said to be not inferior to the Newfoundland; while long training, from generation to generation, to more complicated and important duties, has engrafted on his character the highest degree of canine sagacity, vigilance and patience. Hence " we see in his conduct an instinctive impulse of order, and of care, which are strongly impressed upon the sedate and self-possessed expression of his countenance." We have witnessed with astonishment, says a writer of authority on this subject, "with what rapidity, after a few words, or a sign of his master, a dog of this breed would fly over a vast surface of open country, single out, drive together, and bring up a particular class of sheep from among a large flock, and lead them to our feet. All this was effected without confusion, in a few minutes, and without the least violence."

The portrait here prefixed is supposed to represent •well a specimen of the Scotch collie dog, (already re-commended,) one of which may be seen at "Hereford Hall" near Albany, in the possession of that eminent and liberal cultivator, Mr. Sotham, whose dog, it is said in the "Cultivator," where his likeness may be seen, will perform about all that is attributed to any of the species. We regret that it is not in our power to give his name; and that we were not favoured with an introduction to him on a late interesting and agreeable visit to his hospitable master.

We have been told by General J. T. Mason, who has been much in Mexico, and by Col. Pendleton, late Charge d'Affaires of the United States in Chili, that it is the practice in both Chili and Mexico, to take the pup intended to have the care of the sheep, before his eyes are yet open, and put him to be suckled, and so subsisted on the milk of the ewe.

Of the employment of the Mastiff, also, and his efficient agency in the care of sheep, in Spain, we have, since writing the preceding, been favoured by a friend with the following sketch, going to show that he there effectually takes the place, and performs the offices we have assigned to the Pyrenean or St. Bernard dog. Their temper and character would seem to be almost identical.