DISTRIBUTION OF THE MILLIPEDE TYLOBOLUS-UTAHENSIS CHAMBERLIN, WITH REMARKS ON TYLOBOLUS-FREDERICKSONI (CAUSEY) (SPIROBOLIDA, SPIROBOLIDAE)

Tylobolus utahensis Chamberlin, the only representative of the genus o ccurring in the southwestern deserts, ranges from central Inyo County, California, to the western periphery of Kane County, Utah. This distr ibution roughly corresponds to the northern limit of the Mojave Desert ecosystem and is also shown by the milliped Piedolus utus Chamberlin (Spirobolida: Atopetholidae) and the centipede Theatops posticus (Say) (Scolopendromorpha: Cryptopidae). Tylobolus fredericksoni Causey, ost ensibly from Douglas County, Kansas, is designated a ''nomen dubium'' and disregarded pending collection of fresh material; Narceus gordanus (Chamberlin) is deleted from South Carolina and Tennessee. Tylobolus uncigerus (Wood) occurs north of the Columbia River in Klickitat Count y, Washington, and Hiltonius thebanus Chamberlin is referrable to Onyc helus Cook in the family Atopetholidae.