Update: Thanks to commenters, I learned that these are the work of German artist Heinrich Harder, and the series is titled Tiere der Urwelt, which translates to "Animals of the Prehistoric World." He was an art instructor and landscape painter who became involved in natural history illustrations in the early part of the last century. I'll probably do a future VDA post dedicated to him.
Here's a strange Triceratops; it looks like the artist worked from a verbal description rather than physical specimens. It's much more reptilian than our modern conception of the ceratopsians, with their pebbly skin and occasional quills.
The thirsty hadrosaur: another classic meme of paleoart.
This painting of rhamphorhynchid pterosaurs by the shore at sunset has a great moody feel to it.
Here's a great depiction of the antiquated notion of the "sprawling sauropod." My knees are aching in sympathy for this poor Diplodocus.