220 BACKBONED ANIMALS. 
The eye-openings are placed vertically. They attain a 
length of eight feet, and a weight of twelve hundred 
pounds.* The loggerhead ¢ is nearly as large. Its shell 
is made up of 
scales. They 
breed upon 
Loggerhead 
Key, Florida, 
and other lo- 
calities, bury- 
ing their eggs 
in the sand, 
leaving the sun 
to hatch them. 
Fic. 265.—Green turtle. The digging 
and covering is 
done by the hind-flippers. The green turtle (Fig. 265) 
is somewhat similar, though more delicate, the head and 
flippers smaller. They feed upon alge, particularly Zos- 
tera marina, The hawkbill{ (Fig. 266) is distinguished 
* The gigantic extinct Protostega gigas was allied to the Sphargis. 
It measured seventeen feet between the fore-arms or flippers, and 
was remarkable for the rudimentary character of the bones in the 
adult. 
+ The loggerhead is extremely powerful, and I have found it diffi- 
cult to turn one with the help of two men. By seizing them by the 
shell just over the head I have been carried a long distance in the 
water at a rapid rate. The steeds thus experimented upon were kept 
in an inclosure half a mile long and eight feet deep, and when asleep - 
on the bottom could generally be caught by diving. Owing to their 
sluggish natures they often fall a prey to sharks to the extent of their 
flippers. I have caught them in the Gulf Stream with these organs 
entirely bitten off. 
} Though the hawkbill is a vegetable feeder as a rule, they some- 
times attack the Physalia (Fig. 19). One, two feet long, was found by 
the author floating on the surface, insensible, its head covered by the 
blue tentacles. By scraping them off with a knife the turtle recovered, 
and was kept as a pet for a long time. 
