THE GEOGRAPHIC TURTLES. 73 
M. Jesneuri uvoragcs smaller, yet cxninples are frequently 
seen that measure eio;lit inches in length. 
The only statement concerning dift'erences, therefore, 
that can be accepted without important modification is that 
with reference to the size of the head. The head of M. 
geograjihicuft is very large ; the head of M. lesiieuri is rel- 
atively small. 
De Kay's tigure of ilf . lesueuri is good in the main, but 
the markings about the head, if correctly drawn, were 
from an unusually marked example. I refer to the two 
large, conmia-shaped yellow marks on the side of the head 
posterior to the eye. In the majority of examples, at 
least, there is but one of these marks, the more anterior, 
and it is above the tympanum, never before or Ijehind 
it. 
Dr. Smith (Rep. Geol. Surv. Ohio, iv, 661) describes 
the " head, neck and feet" as slender in both members of 
the genus. The truth is that no member of the family 
Eniydidpe occurring in the United States has a head larger, 
rehitively to the body, than the adult M. geographicus. 
The statement consequently applies to M. lesiieuri alone. 
On page 662 of the same paper the species are character- 
ized thus : 
Head and neck with yellow lines, often reticulated, and 
a single spot on each side or none ; keel not very promi- 
nent. — G. geographica. 
Head with very large yellow blotches or stripes ; keel 
very i)rominent. — G. lesueuri. 
From this we are left to infer that there is a difference 
between the turtles with respect to the markings of the 
head. Yet as far as they relate to such markings the state- 
ments might be transposed without loss in accuracy. The 
head and neck of both are lined with yellow in much the 
same i)atteru. In the great majority of both species also 
ESSEX INST. BULLETIN, VOL. XXU 5* 
