Wied-Neuwied (1865:55-57, Pl. 5) described the species _?G_[_ymnopus_] _olivaceus_, but was uncertain whether his interpretation was based on a species, a variety or a secondary sexual difference. Wied-Neuwied mentioned that Lesueur had already named this soft-shelled turtle as _Trionyx ocellatus_, and agreed with Lesueur that those turtles having occulated spots on the carapace were distinguishable from _T. spiniferus_ and _T. muticus_. But because Duméril and Bibron in their _Erpétologie Général_ failed to recognize _T. ocellatus_, Wied-Neuwied felt obliged to bring it to the attention of his American colleagues and he renamed it. Wied-Neuwied also stated, in the context of a synonym, "Beschreibung einer Reise in Nord-America Bd. I., pag. 140." This comment presumably refers to his earlier description of _T. annulifer_ (1838:140); seemingly Wied-Neuwied considered _T. annulifer_ and _G. olivacea_ as conspecific, although there is no mention of _annulifer_ in the text proper. Stejneger (_op. cit._:49) designated the type locality of _T. annulifer_ as the Ohio River at Pittsburgh, Pennsylvania, and of _Gymnopus olivacea_ as New Harmony, Wabash River, Illinois (_lapsus_ for Indiana). _Trionyx spiniferus_ was questionably considered distinct from _T. ferox_ by Lesueur who listed "Testudo ferox Gm. Tortue de Pennant?" and "Trionyx georgicus Geoffr.?" as synonyms. Subsequently, most authors considered _T. spiniferus_ synonymous with _T. ferox_ until Agassiz (1857) pointed out differences between the two species. The average size of the ocelli on the carapace of the subspecies _spinifer_ decreases westward toward the Mississippi River; ocelli of different sizes occur on different individuals from the same state and presumably from the same population. For example, INHS 2281, plastron 9.9 centimeters in length, from Effingham County, Illinois, has some ocelli eight millimeters in diameter, whereas a larger male from the same locality, UI 1322, plastron 11.6 centimeters in length, has the largest ocelli only five millimeters in diameter. For convenience, all softshells having locality data from states east of the Mississippi River are referred to _spinifer_, recognizing that intergradation occurs with _hartwegi_ over a broad area paralleling the Mississippi River. The type locality of _spinifer_ is in an area where most turtles do not have the larger ocelli (diameter of seven to ten mm. on adult males); however, some individuals from the Wabash River (UMMZ 63523, adult male, plastron 11.5 cm. in length, ocelli diameter seven mm.) agree with more "typical" _spinifer_ to the east. Intergradation with _asper_ possibly occurs in that part of the Tennessee River in eastern Tennessee as exemplified by UMMZ 59198.