506 BULLETIN 38^ UNITED STATES NATIONAL MUSEUM, 



Family CHELONIID^. 



Hard-shelled turtles with paddle-shaped limbs. 



A small groiij) of half a dozen species inhabiting the tropical and 

 subtropical seas, often found hundreds of miles from land, but resort- 

 ing to sandy beaches in order to deposit their numerous round eggs. 

 Full-grown individuals reach an enormous size, 7 feet in length and 

 weighing 800 to 900 pounds. Some species — for instance, the green 

 turtle — are highly esteemed as food, while another furnishes the true 

 "tortoise shell" of commerce. 



Our knowledge of the marine turtles has advanced very little since 

 the time when Doctor Guenther treated of them in his Reptiles of 

 British India (1864). Boulenger, in his Catalogue of the Chelonians 

 in the British Museum (1889), regards the species which are treated 

 of in the present work as identical with the Atlantic forms, though 

 under the loggerhead turtle he makes the admission that the enor- 

 mous variation in a large series "leaves no alternative but to further 

 multiply the number of species or to admit only one." It is not 

 impossible that he found similar alternatives in the other species. 

 My own material is too limited to decide the status of these forms, 

 and under these circumstances I consider it much more rational to 

 enumerate the West Pacific forms under names corresponding to 

 those employed by Guenther and Garman. Such a treatment is much 

 less calculated to cause confusion than the opposite one of joining 

 together those which are not with certainty known to belong together. 



Dr. R. A. Philippi, of Santiago, Chile, has recently described a 

 number of new marine turtles from that country, but the descrip- 

 tions are not sufficiently explicit to justify any judgment as to their 

 actual status. Under these circumstances no attempt has been made 

 to correlate an}" of these new names with those of the marine turtles 

 of the western and northern Pacific. 



Only one species of each genus being known to occur witliin our 

 territory, the key to the genera becomes a key to the species at the 

 same time. 



KEY TO THE GENERA AND SPECIES OF CHELONIID.E OCCURRING IN JAPANESE WATERS. 



a' Costal shields 5 pairs, or more Caret la olivacea, p. 507. 



d~ Costal shields 4 pairs. 



fc' One pair of prefrontal shields Chelonia japonica, p. 509. 



b^ Two pairs of prefrontal shields Eretmochelys squamosa, p. 511. 



