Muskmelon is a generic name for any melon with a netting or "Musk"on it. Cantaloupes such as the French Breakfast, and the Saticoy and Galia are types of Muskmelons.

Muskmelon should be well-shaped and  round and uniform in appearance. There should be no scars or surface defects, and no evidence of bruising. They should appear heavy for size, the surface waxy, covered with a fine netting appearance and not fuzzy. 
U.S. grades are No. 1, Commercial and No. 2. Distinction among grades is based predominantly on external appearances. Sizing is based on count per 13.6 kg (30 lb.) container, most typically 4 or 5, and occasionally 6 melons per carton on up to 15 melons depending upon the variety. High quality appearance is protected, in part, by packing with a partition to protect melons from bruising, compression and scuffing. 
To properly store Muskmelon : 45- 50 degrees F  Storage life is typically 12-15 days at 45 degrees F with up to 21 days attainable. 

Source authorities vary in the reported optimum storage and shipping temperatures for Muskmelon melons. Most recommendations use  45 degree F and 85-90% R.H. as the optimum handling conditions. In general, if melons are ripe or pretreated with ethylene at 100 ppm for 24 hr, trade recommendations for short-term storage and shipping are often range from 36.5 - 41 degrees F. Extended holding at these temperatures will induce chilling injury, rapidly evident after transfer to typical retail display temperature 

Here are some good links for Muskmelon information:
http://www.hort.purdue.edu/newcrop/id-56/vinecrops.html

http://www.ag.ohio-state.edu/~ohioline/b672/b672_22.html

http://www.hort.vt.edu/faculty/welbaum/pictures/11-1.html

http://gianteagle.com/makesmpl/farmer/previous/melons.htm