The Lost Pines forest of East Central Texas is a relict ecosystem of the last glacial age that ended 10,000 years ago. A crossroads mixture of flora and fauna classified as Eastern, Western, Central, Southern, Widespread, and Introduced is the result of a Pleistocene expansion from the southeastern United States combined with the ecosystem's marginal position along the east-west biogeographical divide and its location in the central plains corridor and at the northern extremity of Neotropical species ranges. For invertebrates at large the modal biogeographical affinity is eastern, with widespread taxa next in abundance but with much smaller contributions from the remaining four categories. Nine additional analyses at the taxonomic level and one analysis at the level of species dispersal ability are included in addition to comments on invertebrate groups represented by only one or a few species.