102 G.R. Wieland— On Marine Turtles. 



certain to be made. Moreover, to all these newer facts and 

 viewpoints we are enabled to add the description of a new 

 species, calling for analysis of the gronp. 



To these forewords to the present revision I wish to add 

 praise for the painstaking labor bestowed upon the mounting 

 of Archelon by the Yale Museum preparator Mr. Hugh 

 Gibb. Likewise we are indebted to the rare skill of the well 

 known scientific illustrator and artist Mr. P. Weber for the 

 illustrations following. 



CHELONIOIDEA Baur. 



SUPERFAMILT OF THE CrYPTODIRA. 



A parieto-squamosal arch ; palatine foramen and free nasals 

 sometimes present (Desmatochelyidge); fourth cervical cyrtean, 

 with the centra of the sixth to eighth less modified in Creta- 

 ceous than in recent forms. 



The five great marine families, namely, the Cheloniidse, 

 Protostegidse, Desmatochelyidse, Toxochelyidee, and Dermo- 

 chelyidse, all doubtless independently acquired their equipment 

 for life in the sea. ]5 



Family Protostegidce Cope. 



Turtles with highly specialized thalassic humeri, but with 

 three or more claws. A leathery hide and osteodermal arma- 

 ture evidently present. Carapace usually greatly reduced in 

 later forms, the disk investing less than one-half the rib lengths. 

 Plastron not markedly reduced. Peripherals serrate to 

 strongly digitate on their interior borders ; intra-peripheral 

 dermogene ossicles sometimes present (known in Archelon 

 only). Plastron very large, dactylosternal, with prominent 

 fontanelles ; epiplastra small, out-turned, separate, and wholly 

 supported by the very large T-shaped entoplastron ; hyo- and 

 hypoplastra moderately digitate (Protostega advena) to strongly 

 digitate {Archelon) ; xiphiplastra short and bowed. Pelvis 

 with obturator foramina enclosed by complete ischio-pubic 

 border. Coracoid extending all the way back to the pre-pubis 

 except possibly in P. Copei. Skull large ; temporal region 

 broadly roofed over ; descending processes of parietals ; ant- 

 orbital projection marked ; quadrato-squamosal vertex much 

 depressed ; narial aperture more or less upturned ; choanae far 

 forward, opening free behind vomer. 



Genus Protostega Cope, 1872. 1 

 Premaxillary beak less developed than in Archelon / maxilla 

 with rather broad grinding surface, which extends backward 

 to behind front of orbit. Lower jaw with rami early coossi- 



