In the online version of the
Haydock Catholic Bible commentary, the transcriber has tried to expand some of the original abbreviations for ease of understanding.
“C.” or “c.” followed by Roman numbers (in lower case letters) almost always stands for “Chapter.” Thus, for example, “C. iii. 5.” almost always means “Chapter iii., verse 5.” of some book. Which particular book is determined from the context. Here are some examples:
Example #1: On Matthew 1:12, the Haydock commentary reads:
In comparing the present genealogy with that of S. Luke, (C. iii.) we find that in this last part S. Matthew has suppressed many generations, to bring the list to the number 14; for there are a greater number from Zorobabel to Jesus Christ in S. Luke, but in a different branch. V.
In this case, with its reference to S. Luke, “C. iii.” means “Luke, chapter iii.”
Example #2: On Matthew 2:15, the Haydock commentary reads:
S. Jerom understands these words to be taken out of the prophet Osee, (C. xi. 2.) and granted they might be literally spoken of the people of Israel: yet as their captivity in Egypt was a figure of the slavery of sin, under which all mankind groaned, and as their delivery by Moses was a figure of man’s redemption by our Saviour Christ, so these words in a mystical and spiritual sense apply to our Saviour, who in a more proper sense was the Son of God, than was the people of Israel.
In this case, with its reference to Osee, “C. xi. 2.” means “Osee, chapter xi., verse 2.”
Example #3: On Matthew 10:22, the Haydock commentary reads:
We are also assured of the same truth in Ezechiel.
If the just man shall turn away from his justice, and shall commit iniquity, he shall die in his sins, and his justice which he hath done shall not be remembered. C. iii, v. 20.
In this case, with its reference to Ezechiel, “C. iii, v. 20.” means “Ezechiel, chapter iii., verse 20.”
Example #4: On Matthew 21:2, the Haydock commentary reads:
Here was manifestly fulfilled the prophecy of Zachary. C. ix.
In this case, with its reference to Zachary, “C. ix.” means “Zacharias, chapter ix.”
Example #5: On Luke 21:37, the Haydock commentary reads:
In this last week, Christ, after preaching in the day-time in the temple, when constantly in the evenings to pray in the garden of Gethsemani, as Judas knew very well. See C. xxii. v. 39.
In this case, which lacks an obvious reference to another book, the same book (Luke) is to be understood, so that, “C. xxii. v. 39.” means “Luke, chapter xxii., verse 39.”
If you are still having trouble with a particular citation, I would be happy to help you try to decipher it.