Five of 32 apparently healthy deer, Odocoileus virginianus, were shown to harbor L. monocytogenes in their alimentary tracts. Cultural, biochemical, serologic and virulence characterizations of the five fecal isolates of L. monocytogenes are presented. It is believed that these isolates are the first described from the alimentary tract of apparently normal deer. Two deer harbored serotype I strains of L. monocytogenes, the other three yielded serotype IV strains.

Examination of 2,440 deer in the Catskill Region and 609 in the Adirondack Region revealed skin tumor prevalence of 1.4 per cent and 1.3 per cent respectively. A total of 37 or 88.1 per cent of the infected deer from these two areas were males. Infections involving five or less small tumors were most frequently encountered.

Nymphs of Porocephalus crotali were found in 20 (0.9%) of 2,254 mammals examined from localities in 22 counties in Florida. Of 27 species included in the survey, infections were found in the Florida mouse, Peromyscus floridanus; cotton mouse, Peromyscus gossypinus; and cotton rat, Sigmodon hispidus. The last two species represent new intermediate host records for this parasite. Based on total individuals examined, incidence was 0.6, 4.3, and 0.2% in P. floridanus, P. gossypinus, and Sigmodon, respectively. Considering only samples from localities at which infections occurred, prevalence was 1.8% in Florida mice, 13.9% in cotton mice, and 1.0% in cotton rats. There was some evidence of a higher infection rate in males than females of P. gossypinus but not in P. floridanus. Over half of the infected rodents examined had more than a single nymph, the maximum number recorded being 85. Nymphs occurred at numerous sites in the viscera, mesenteries and walls of the body cavity. Infected animals did not appear to be seriously affected by the parasites, and it is concluded that, except perhaps under conditions of severe environmental stress, P. crotali probably does not play an important role as a mortality factor in host populations in Florida. The majority of infections came from a single habitat type; the basis for this restriction is not clear. The data show some suggestion of a higher prevalence rate in the warmer months of the year.