NEW YORK -- J. Crew Group (JCG) said Tuesday its third-quarter earnings fell 29% on lower sales at existing stores and slimmer margins, but the results still topped analysts' expectations.The retailer also slashed its earnings prediction for the full year, citing the tough economic environment. During the third quarter, the apparel retailer earned $19 million, or 30 cents per share, compared with $26.8 million, or 42 cents per share, in the year-ago quarter. Revenue rose 9% to $363.1 million from $332.7 million. Analysts expected a profit of 27 cents per share on revenue of $351.2 million, according to a poll by Thomson Reuters. J. Crew said its gross margin fell to 41.6% of revenue, compared with 45.6% of revenue in the prior-year period. Same-store sales, or sales at stores open at least a year, fell 3% in the period. Same-store sales is a key retail performance indicator because it measures sales at existing stores rather than newly opened ones. J. Crew shares climbed $1.07, or 10.7%, to close at $11.05. But in aftermarket activity, the stock slid $1.04, or 9.4%, to $10.01.