The Maryland Jockey Club Races commenced yesterday, when the "Dorsey Stakes" were run for.  Of the sixty-two colts subscribed for, forty-eight forfeited and fourteen ran.  The first mile heat was won by Robinson's colt, by Loughborough; the two last by Win's colt, by the same sire.  The sweepstakes and forfeits amounted to the proper sum of nine thousand dollars.  The morning was wet and unpromising but before the race commenced, the rain subsided.  The running is spoken of in terms of great approbation by the gentlemen of the turf, and all passed off to the decided satisfaction of those present.