ttest

This is for a college biology class. The class went out and did a count on the amount of species in different areas, with three repetitions in each area. Now that all the data are gathered (in an Excel file), it is time to write a report. I have a hypothesis that state species A exist more in...

do you use when df=212? Basically the standardized char max's out at 120 or infinity. I have df=212 and assume I should be referring to df=infinity when finding my t-value. Is this true or should I be using 120? Thanks!