I hadn't seen this challenge when I visited Colchester on 1st January, so missed a few, will get them next time :
1. Geoffroy's marmoset
2. Golden Lion Tamarin
3. Golden-headed lion tamarin
4. Red Titi
5. Colombian black spider monkey
6. Common squirrel monkey
7. Red backed Saki
8. Chimpanzee
9. Bornean Orangutan
10. Patas monkey
11. L'hoest monkey
12 Mandrill
13. Pygmy marmoset
14. Pileated gibbon
15.ring-tailed lemur
16. Lion-tailed macaque
17. Cherry - Crowned mangabey
18. Yellow -breasted capuchin
19. Gelada
Linton 2nd January
20. Cotton - top tamarin
21. White -collared lemur
22. Mongoose lemur
23. Crowned lemur
24. Red Ruffed lemur
Shepreth 22nd January
25 Pygmy Slow Loris
26. Crab-eating Macaque
27. Grivet monkey
28. Red-bellied Tamarin
29. Black & white Ruffed Lemur