Hi, ALL!

I am reading now  a glittering, reputable National Geographic
magazine ("100 greatest mysteries revealed"), and in the article
about King Arthur I read:

-----Beginning of the citation-----
Historical opinion is now split. Some scholars think
that the lack of contemporary accounts of Arthur mean
he is a later invention.
----- The end of the citation -----

1. What about the absence of article before "Historical opinion"?
2. why do they write "mean" instead of "means"?

IMHO the lack of ... means...

Bye, ALL!
Alexander Koryagin

---