Design For Doomsday by Bryce Walton

There are no adventures in space. Either a space-flight is safe monotony, or quick death. But as the two Guardsmen approached the vast mysterious dome of S. S. C. somewhere in the Mesozoic nightmare, the vaporous, steaming, endlessly stretching rain-forest of Venus, they stumbled with wracking weariness. Reptile-infested swamps and steaming seas, foul-smelling, rotten -- it was an incredibly perilous planet.

For five hours they had burned their way through giant flora and fauna and sweat, H-guns hot with almost steady usage. And then Venard finally parted some phosphorescent, glowing lichen and there the gigantic dome rose up and up and lost itself in thick mist. But between them and their goal was a hellish nightmare barrier, spilling stinking muck into a placidly steaming sea.