In the back of book exercises Ch. 34, #25:
Ea nocte profectus, Caesar ad quandam insulam clarissimam venit.
I was confused by the use of quandam, and the glossary had no answer. Then I understood: quandam was really quamdam with the 'm' becoming an 'n', just like eamdem becomes eandem. Wheelock did not mention this (maybe he wanted the reader to figure it out).