(1) The otic capsule (= periotic bone) of the dog ossifies from a number of centres, one of which is equivalent to the frog's prootic.
(2) The several constituents of the lower jaw are not to be distinguished in the adult mammal.
(3) The frog has no lachrymal bone.
Text Book of Biology, Part 1: Vertebrata · The Wunder Library — complete classics, free to read, with narration.