MUSK TORTOISE. 667 
ginals much the higher, making an upward curve or indentation into the posterior cos- 
tal on each side; last vertebral quadrangular, broadest behind, with a slight projection 
downward between the two posterior marginals; first neural elongated, broadest 
anteriorly ; vertebrals slightly imbricated, alternating with the costals ; carapax slightly 
emarginate behind, arched upward over the neck; gular plate nearly triangular, the 
remaining sternal shields more or less quadrilateral; abdominal much the largest; tail 
short, with several rows of pointed warts; neck, legs, and feet granulated; fore legs 
with scaly plates, and bases of feet with scales; no plates on the posterior limbs. 
Length of carapax, 44 inches ; height of carapax, lZinches; breadth of carapax, 3 inches; 
length of tail, 1 inch. 
Habitat, Maine, Massachusetts, New York, South Carolina, Georgia, Florida, Alabama, 
and Louisiana, to Tenifessse, Ohio, Michigan, Indiana, and Missouri. 
The Musk Tortoise inhabits ditches and ponds, burying itself in mud. 
It is an active animal, and bites with considerable vigor if irritated. It 
has a very disgusting odor from which, with its habits, it has received 
not only its specific, but also its various common names, such as Musk 
Turtle and Stinkpot in the north, and Mud Terrapin in the south. It 
occurs in Northern Ohio and probably also occasionally through the 
whole State. It oviposits in June and. July. 
FAMILY TRIONYGCHIDA. THE SOFT-SHELLED 
TU ay Se 
Carapax in the form of a flattened orbicular disk, never completely oxsified, ite mar- 
gins soft and flexible, and in some species with the ribs projecting; costal plates when 
visible eight pairs; postericr margin of carapax extendiag much beyond the body; 
sternum composed of four paira of bones and one odd one; plastron a leathery covering 
with or without the sternal bones being visible externally; feet broadly palmate; head 
and neck very long and flexible; nostrils carried forwards by a long tubuaiar projection ; 
temporal arch narrow ; parietal bones slightly if at all projecting outward; pterygoids 
broad, with slight depressions on their external edges; sphenoids extending forward 
between the pterygoids to the palatines ; inner nares large, and situated far back. 
The Trionychide are usually found at the bottom of shallow water buried in mud. 
They remain thus buried, raising their head and long flexible snout to the surface for 
the purpose of respiration. Thus the long flexible neck, head, and snout as well as the 
soft covering correspond to the habits of the animal, ag a hard carapax and plastron 
are unnecessary fer the purposes ef protection to them whils buried in the mud. In 
burrowing they go under a thin layer horizontally by digging with the fore feet, brac- 
ing and pushing the bedy under with the hind ones. 
*Septum ef nese without any internal ridges on each side. . . 5 AMYDA., 
* Septum of nose with a ridge en each side. . : 4 : .  ASPIDONECTES, 
Genus AMYDA. Schweigger. 
Head long, narrow, aad pointed anteriorly ; horizontal alveolar surface of jaw nar- 
row, broadest behind, and with a downward curve of the upper under the eye; lower 
