POSIX

Unlike most other answers here, these work on any POSIX system, for any number of files, and with any file names (except where noted).

Lines in each file:

find . -name '*.php' -type f -exec wc -l {} \;
# faster, but includes total at end if there are multiple files
find . -name '*.php' -type f -exec wc -l {} +

Lines in each file, sorted by file path

find . -name '*.php' -type f | sort | xargs -L1 wc -l
# for files with spaces or newlines, use the non-standard sort -z
find . -name '*.php' -type f -print0 | sort -z | xargs -0 -L1 wc -l

Lines in each file, sorted by number of lines, descending

find . -name '*.php' -type f -exec wc -l {} \; | sort -nr
# faster, but includes total at end if there are multiple files
find . -name '*.php' -type f -exec wc -l {} + | sort -nr

Total lines in all files

find . -name '*.php' -type f -exec cat {} + | wc -l