7 
point was first stressed by Williams in his 1960 paper, and no 
novel contribution has been made since to the matter. There are 
thus two problems to consider: the topo-ecological distribution of 
the forms in the open formations and the rationale of their overall 
distributions. Whether both species of Geochelone follow an Iguana 
iguana model (Trajano and Ghiringhello, 1978), egually at home and 
with no apparent morphological differentiation in the forest and in 
open, even semiarid situations, or are limited in the latter to 
gallery forest or wooded enclaves, is a matter to be settled by so 
far nonexistent field work. 
On the other hand, this independence from morphoclimatic 
domains has been well discussed by Heyer (1979) for species of 
Leptodactvlus . These have been shown by serological methods (Heyer 
and Maxson, 1982) to be old, mid-Tertiary species, immune to 
Quaternary cycles of speciation related to climatic events. I 
would guess that the two Geochelone in guestion tend to follow this 
model. However, a study of their geographical differentiation 
demands collections covering the entire area with samples amenable 
to statistical treatment. This is clearly not the present 
situation. 
PHRYNOPS GEOFFROANUS IN AMAZONIA 
Pritchard and Trebbau (loc. cit .: 115) in their figure 19, 
"Distribution of Phrynops geoffroanus ", show a wide hiatus in 
Brasilian Amazonia. We have one specimen, MZUSP 2682, collected 
(19 September 1969) at Alter do Chao (02°32'S, 54°57'W), Para on the 
Rio Tapajos (Map 3). I captured this specimen at night on a beach; 
the late Fred Medem, my companion on that field trip, autopsied the 
turtle, a female with ripe eggs, and kept notes. 
The importance of this find is not so much the range extension 
itself, but the indication that the species is rare or hard to 
find. The Tapajos has been very thoroughly collected by many 
herpetologists, and this is the only specimen so far. In these 
conditions, negative distributional evidence must be used with much 
discretion. 
TYPE LOCALITY OF PLATEMYS RADIPLATA 
AND 
COMMENT ON P. SPIXII 
Rhodin, Silva and Mittermeier (1984), in a study of the 
distribution of Platemys radiolata and spixii (both now 
Acanthochelvs ) cite the type locality of the former as Sao Paulo: 
Sebastianopolis (= Sao Sebastiao) (23°45 , S, 45°25 , W)". This 
