THE ANATOMY OF SOFT-BILLED TURTLES, 403 
in general, easily be traced upon the interior of the carapace. But 
the most marked results of this defective ossification is the entire 
separation of the eighth pair of ribs from those anterior, they being 
held in position only by dense fibrous investment. This is entirely 
different from what we are led to expect; for Cuvier, in remarking 
upon the carapace of this genus (‘Ossemens Fossiles,’ tome 1Kay 
p- 398), observes that “There are eight pairs of ribs, wnited by 
sutures, which in these, as well as in the Marine Turtles, are not 
dilated to their outer end, but of which the dilation extends with 
the age of the individual.” 
The relation of the alimentary canal to the size of the reptile, 
too, varies considerably from the proportions taught. Ina specimen 
two feet in extreme length, the entire length of the digestive 
apparatus was exactly four feet, divided as follows :—(Esophagus, 
nine inches; stomach, six; small intestine, twenty-seven; and 
colon, including the cloaca, six inches only—this absolute and 
relative length of the tract indicating a purely carnivorous diet on 
the part of its possessor. Cuvier gives the relative length of the 
alimentary tract to the body, as observed in the Emydide, as five 
to one; and Rymer Jones, in contrasting the carnivorous with the 
herbivorous Testudinata, remarks that the “ Emydide are more 
carnivorous in their habits, and in the Trionychide the alimentary 
canal is shorter—at least the larger intestine, which is not longer 
than the small.” -With Aspidonoctes, the large and small intes-’ 
tines, as we have seen, vary materially in length; but they are 
almost continuous with each other, no angle being formed at the 
junction, and the separation marked only by a slight valvular 
constriction: the former, too, though possessed of a trifle greater 
diameter, is much less muscular than the small intestine, and 
consequently more distensible. 
Again, Cuvier remarks that in those genera of the order other 
than salt-water Turtles, “ the esophagus presents only longitudinal 
folds and numerous orifices of mucous crypts.” But in the species 
under consideration we find the greater portion of the gullet covered 
with bifid fringe-like processes; and upon the fauces, the upper 
portion of the larynx (rma glottidis), and the arches of the hyoid 
bone, presenting both the character and arrangement of those of 
the tongue, before noted as resembling the gills of the Meno- 
branchus, or more properly, perhaps, the internal ciliated 
respiratory apparatus of the Tadpole. 
