I have several baby cantelopes growing, about an ...

It is difficult to really diagnose this problem without knowing more about your soil, weather and watering conditions.  It could be a problem with any or all of them.  Cantaloupes and other melons like a rather dry soil to start out with and then when they bloom and start to produce like more water--given at the base of the plant on the ground--no sprinklers.  Are they in full sun?  (at least 6 hours of sun a day)?  Also are the melons on a vine or a bush?  And are the melons resting on the ground itself or are they suspended above ground?  There can be many problems going on.  What I do suggest is that you take a sample of the production to your local county extension agency office to get an accurate and precise diagnosis.  The phone number can usually be found in your county office pages.  Good luck.

I had this same experience, and in my case, it was due to two problems; overwatering and not enough root space (I was experimenting with intensive gardening, and made the mistake of planting them in the same bed with cucumbers, which like a LOT of water).  As Kathy says, though, there could be any number of causes.  How closely are they planted?  How often do you water?  How much sun do they get?  How much nitrogen is in your fertilizer?  Are they trellised, or spreading on the ground?  The first few female blooms often do not set fruit; how old are the plants?

I'll offer another explanation: In our section of the country, we are having severe problems with melons and squash due to lack of pollinators.  Yep, our little world-wide bee problem is becoming really noticable now.  The fruit starts, but then shrivels up because it hasn't been properly pollinated.  You can try hand pollination to see if that solves your problem, or you can spray with bee pheromones to help attract more bees.