Pleistocene Mammals Central Florida 73 



Order Lagomorpha 

 ' Family Leporidae 



Sylvilagus sp. Gray 1867 



Material— Left dentary with P3-P4, M2-M3 (V-4467); proximal 

 femur (UF 49201); distal femur (UF 49202). 



Remarks., — Two species of similar-sized cottontails, Sylvilagus 

 palustris and S.floridanus, presently range throughout most of Florida. 

 The distribution of a third, much larger species, S. aquaticus, closely 

 approaches the Florida panhandle in Alabama; quite possibly the spe- 

 cies has recently extended its range into extreme western Florida. Left 

 mandibular toothrow lengths were measured in five specimens each 

 (mixed sex) of modern S. palustris and S. floridanus from Alachua 

 County, Florida, in efforts to assign specific identity to the Rock 

 Springs rabbit material. The sample mean for toothrow length for S. 

 floridanus is 15.20 mm (s = 0.29 mm) and for S. palustris is 15.24 mm (s 

 = 0.45 mm). Toothrow length in the Rock Springs specimen is 14.9 mm. 

 Lack of mensural differences between these three samples dictates refer- 

 ral of the Rock Springs rabbit to Sylvilagus sp. 



Order Rodentia 



Family Geomyidae 



Geomys pinetis Rafinesque 1817 



Material— Isolated upper P4, (UF 49205). 



Remarks. — Geomys pinetis is the only extant pocket gopher in the 

 eastern United States. The southeastern pocket gopher is presently 

 abundant in the vicinity of Rock Springs, and in other parts of the 

 southeastern United States characterized by the longleaf pine-turkey 

 oak sandhill ecosystem. Despite the limited referred material, its generic 

 identity is certain. Extant Geomys species possess an enamel band on 

 the posterior surface of the fourth upper premolar. This posterior 

 enamel investment on upper P4 is absent in Thomomys species and in 

 the early-to-middle Irvingtonian species of Geomys in Florida (Wilkins 

 1984). 



Thomomys cf. orientalis Simpson 1928 



Material — Six mandibles with partial to complete dentitions (UF 

 46571-46576). 



Remarks. — Generic assignment of these specimens is indicated by 

 the presence of both anterior and posterior enamel bands on the lower 

 molars; anterior bands are absent in Geomys species. The genus Thom- 

 omys presently occurs in western North America (Hall 1981). The only 



