jx CHELONIDAE 387 



officer thirty years before, with a view of establishing the fact 

 of these recurring visits to the same beach. The same homing 

 instinct has been observed in some females of the Green Turtle, 

 which, having been brought from the Tortugas Keys to Key 

 West off the south end of Florida, escaped, and v/ere, a few days 

 later, re-caught at the Tortugas. On the other hand, experi- 

 ments made with turtles at Ascension are said to have had no 

 result. 



Thalassochelys, with five pairs of costal shields. The carapace 

 is completely ossified in the adult, leaving no fontanelles between 

 the ribs and the marginals. 



Th. caretta (the " Loggerhead Turtle "). — The shields of the cara- 

 pace imbricate only in young specimens, in the adult they become 

 smooth and juxtaposed. The margin is serrated posteriorly. 

 The carapace of the young has three strong keels. The inter- 

 gular shield is very small or absent. The marginals, including 

 the nuchal, usually number 23, rarely 25. The large head is 

 armed with hooked jaws, the crushing surface of the horny upper 

 beak has a median prominent ridge. The top of the head has 

 a pair of shields in front of the unpaired frontal. The flippers 

 of the young have claws on the first and second digits ; in the 

 adult usually only that of the first digit remains. The general 

 colour of the shell is uniform brown above, yellowish below. 

 Very young specimens are uniform dark brown or blackish above 

 and below. 



Large individuals have a shell about three feet and a half in 

 length. The Loggerhead is carnivorous, and is commercially of 

 no value. Its habits seem to be the same as those of the other 

 Turtles, but it has a much wider distribution. Besides all the 

 tropical and intertropical seas, it inhabits the Mediterranean, 

 and is an accidental visitor to the western coasts of Europe, 

 especially Portugal and the Bay of Biscay. It has been caught 

 several times on the coast of Belgium, and an old female con- 

 taining 1150 eggs was captured in 1894 on the Dutch coast. 

 In 1861 one was caught near Penman, on the coast of Banffshire, 

 and a second in the completely land-locked Loch Lomond.^ 

 It has been more frequently recorded from the coast of Devon 

 and Cornwall. 



The most interesting feature of the Loggerhead is the 



1 Xotes Leyden Mus. xvi. 1895, p. 211. 



