This example displays the Iris dataset as a scatter plot, mapping sepal length to the x-axis and petal length to the y-axis, with each species distinguished by a different symbol shape from `d3.symbol` and `symbolsFill`. The `d3.scaleLinear` and `d3.scaleOrdinal` functions handle the spatial and categorical mappings, while `d3.axisLeft` and `d3.axisBottom` generate the axes. The species data is loaded from a remote CSV file and parsed with `d3.csvParse`, with a custom legend built using `d3.symbol` to identify the shape categories.