What does "ingens patebat tellus" mean?

In the prefatory remarks of Thackeray's Book of Snobs is written:

"When a man has this sort of vocation it is all nonsense attempting to elude it. He must speak out to the nations; he must unbusm himself, as Jeames would say, or choke and die. 'Mark to yourself,' I have often mentally exclaimed to your humble servant, 'the gradual way in which you have been prepared for, and are now led by an irresistible necessity to enter upon your great labour. First, the World was made: then, as a matter of course, Snobs; they existed for years and years, and were no more known than America. But presently,—INGENS PATEBAT TELLUS,—the people became darkly aware that there was such a race. Not above five-and-twenty years since, a name, an expressive monosyllable, arose to designate that race. That name has spread over England like railroads subsequently; Snobs are known and recognized throughout an Empire on which I am given to understand the Sun never sets..."