The numerical and temporal occurrence of the nematodes is summarized in Table 2. It should be noted that of the 17 worms constituting the maximum infection by _Thelandros_, only one was an adult worm; the maximum number of adult _Thelandros_ in any one host was five. Similarly, the heaviest _Oswaldocruzia_ infection, 15 worms, consisted of immature individuals; the maximum number of adult worms in any one host was ten. The monthly variation in the relative occurrence of young stages _versus_ adult in both nematodes (Table 2) suggests that the parasites are eliminated from hosts sometime in the long period, late September to early June, when _A. hardii_ exists subterraneously; the worms thus would be reacquired annually when the salamanders resumed living on the "surface" or near the surface. Table 2 shows that the majority of the worms are immature (100 per cent, in _Oswaldocruzia_) in samples taken in July. Additionally, all but one individual of those constituting the 20 per cent occurring as immature _Oswaldocruzia_ in the period August to September were actually collected in early August. These were found in one salamander, and this constituted the heaviest infection for the period; crowding effects may have led to retardation of development of the worms. If it is true that parasites are reacquired each spring--we assume that no temperature factors or immune reactions are delaying development of the worms, and no unusually long external ovic or free-living phase is a necessary part of their life-history--then the host-parasite data can be used as a basis for hypothesizing about the winter life of the salamander. During "surface" life the incidence of parasitism is high (90 per cent and 83 per cent: see Table 2), indicating that salamanders are readily invaded in times of activity. Salamanders examined in September were all parasitized and probably carried nematodes with them into their winter retreats. This part of their habitat should thus be contaminated with infective stages of both parasites. Yet the salamanders seem to become re-infected when the period of summer activity starts (note the high incidence of immature parasites in salamanders taken in July); therefore, the salamanders lose their worms in winter. This suggests that during their subterranean life salamanders are inactive, and avoid ingestion of infective stages of the parasites. A fairly complete hibernation such as we suppose they undergo has been reported by Szymanski (1914) for _Salamandra_ on the basis of kymographic records of movement. Characteristics of Breeding _Sex-ratio_