A quantitative analysis of several onychophoran characteristics shows that in habitats with lower rain levels females reproduce at an older age, are more fecund and tend to have reproductive diapause where rain does not exceed a mean of 200 cm/year. These habitat characteristics are associated with the southern family Peripatopsidae. Sex ratio and parental investment per young are not correlated with general environmental conditions. A comparison of 72 species showed that larger species are often more variable in morphometry, but species with the longest females do not always have the longest males. Larger Peripatus acacioi females (Peripatidae: Brazil) produce more and heavier off spring. Intrapopulation morphology was studied in 12 peripatid species for which samples of between II and 798 individuals were available. In general, within populations the females are more variable than males in’ length and weight, but similarly variable in the number of legs. The number of legs has a low variability (1.73- 2.45%). length is intermediate (22.4-25.3%) and weight is very variable (49.41-75.17%). When sexes are compared within a population, females can have 14-8.9 % more leg pairs, and be 47-63 % heavier and 26 % longer than males.
