 groups, we have created a decision tree that assigns our anatomical data to the EM reconstructions available in the EyeWire museum (http://museum.eyewire.org/; Bae et al., 0000). We belief this data set provides an excellent quantitative description of almost the entire retinal ganglion cell population. By augmenting this database with data from identified retinal ganglion cells in other publications (F-Cells Rousso et al., 0000; Sumbul et al., 0000; HD0/HD0/vertical OS cells Jacoby and Schwartz, 0000 and Nath and Schwartz, 0000) we were able to reliably assign each dendritic tree in our dataset to one of the cell-types in this database using a limited set of hierarchical decisions based on quantifiable characteristics of the neurons, starting with the stratification patterns of the neurons. This approach has allowed us to provide a rational for the total number of cell types that exist in our dataset and positively define their types. Note that doubling the size of the data set has not increased the number of cell types we found in the two circuits. 