This paper records the presence of a new species of trypanosome in the lizard Uranoscodon superciliosa L. (family Iguanidae), caught near Codajaz, Amazonas, Brazil, in August 1964 during the Guy's Hospital Expedition to the Lower Amazon.
Examination of a methanol-fixed and Giemsa-stained smear of blood taken from the heart of the lizard showed a heavy infection of trypanosomes. Camera lucida drawings of twenty were made, measurements being determined with dividers and a map-measuring wheel. The animal was preserved in 10% formalin, portions of liver, spleen, brain, heart, and lung being later extracted. Sections 5 μ in thickness were cut and stained in Ehrlich's haematoxylin and eosin, and in Giemsa's stain.
The chief distinguishing feature of the trypanosomes was their comparatively enormous size, up to 124 μ in total length, including the free flagellum, and 19 μ in width. The cytoplasm stained deep blue in Giemsa's stain, there being little indication of any vacuoles or inclusions. The posterior end was generally less intensely stained, and in certain cases pale, narrow, channel-like extensions from this region forward into the main body of the organism could be detected (Fig. 1). The nucleus, elongated and rather variable in shape, was distinguished by being less deeply coloured than the surrounding cytoplasm; it lay slightly posterior to the mid-point of the body, its longest diameter being parallel to the longitudinal axis of the animal. The kinetoplast, situated slightly posterior to the nucleus, was usually of circular shape, staining deep red; from it arose the flagellum, which passed forward along the margin of an undulating membrane and terminated in a free portion at the anterior end. Measurements of the organisms are given in Table 1.