A scatter plot of the Iris dataset encodes each observation as a distinct SVG symbol, with circles, squares, and triangles mapping to setosa, versicolor, and virginica species respectively. D3 scales map petal length and sepal length to Cartesian axes, with color and shape encoding species via `d3.scaleOrdinal` and `d3.symbol`. The visualization renders the data as SVG paths selected via `d3.symbol().type(...)`, includes axes using `d3.axisBottom` and `d3.axisLeft`, and displays a legend for the species shapes.