ACROSS
7. NASA probe of a gas giant
8. Vermiform process connected to the cecum
9. Macropus member
10. Occasion for a student to use a blue boo
11. Designer of early steam-powered ships
13. More than a hypothesis
15. Happening in springtime
17. Turdus member, like the American robin
18. Ungulates of the Serengeti
20. World's largest living rodent
22. Freshwater fish named for its coloration
23. Natural thermonuclear fusion site
DOWN
1. Sedative of the quinazolinone class
2. Pioneering 1972 video game from Atari
3. Network of rabbit burrows
4. Deracinate from the garden
5. Where to find semicircular canals (2 words)
6. Virus named for a forest in Uganda
12. Chemical element also known as wolfram
14. Cultivator of thorny bloomers
16. Type of acid in sour milk
17. Swamp...