Extended ACL for a portion of a subnet

I want to know if I can write an ACL that will block the upper portion of a subnet. Example: I want to block telnet access form the lower portion of subnet 171.17.4.128/26. I have the lower subnet portion going to machines to the Internet but I want to block telnet from 129-159 and allow all others. I am not sure how to do the wildcard mask for this? Any help will be greatly appericated.