As a general rule, in red blooded animals furnished with feet and not oviparous, the male is larger and longer lived than the female (except with the mule, where the female is longer lived and bigger than the male); whereas in oviparous and vermiparous creatures, as in fishes and in insects, the female is larger than the male; as for instance, with the serpent, the venom spider, the gecko, and the frog.