112 G. R. Wieland — On Marine Turtles. 



specimen lias been of considerable value in showing the more 

 important carpals in natural position, and in yielding additional 

 linger bones and the epiplastron. A well-conserved lower jaw 

 with fully coossitied rami accompanies it. Like the type, it 

 was completely imbedded in one of the lenticular masses of 

 marl or clayey limestone common in the Pierre, but as this 

 was much checked by cleavage planes there has been consider- 

 able shifting of parts. The specimen, while good, is not com- 

 parable to the original type, which, barring the lack of the 

 skull (destroyed by erosion), is one of the finest of all great 

 fossil vertebrates. It was but little crushed, and nearly all 

 the parts present were in their normal position. 



In addition to the examples mentioned, fragmentary portions 

 of other specimens were obtained at different times, all per- 

 taining to the uppermost one hundred feet of the Pierre, and 

 all from within an area of about eight square miles. The best 

 skeletal conservation was found in the bluish clays of the 

 upper thirty feet of the Pierre, as covered by the Oligocene 

 overlap in the Cheyenne Kiver valley ; but most unfortunately 

 a broad Oligocene river, the clearly marked bed of which I 

 definitely located west of the Cheyenne, scooped out of these 

 Pierre strata exactly the portion that must once have con- 

 tained the most numerous and the best turtles, as indicated 

 by frequency of occurrence as well as fine conservation on both 

 banks of the old Oligocene valley. 



The various specimens of Archelon have been made the sub- 

 ject of five contributions to this Journal. 6) 8> "• ,2 ' 14 . These par- 

 tial descriptions have been repeated in a summarized abstract, 

 with certain additional interpretations and views, in Dr. Hay's 

 great volume on the " Fossil Turtles of North America." 17 

 It does not therefore seem necessary again to repeat the 

 preliminary descriptions, except in so far as needed to call 

 attention to inaccuracies disclosed by the final mounting of the 

 type specimen, together with the great additions to our knowl- 

 edge of Protostega made during the past half dozen years. 

 It is the present purpose to give in concise form the features 

 of this greatest of marine turtles disclosed by new discoveries 

 and by mounting, which always sheds new light on the char- 

 acters of a fossil vertebrate ; and especially to give the facts of 

 classificatory value, together with a discussion of relationships. 



The Skull (figure 6). — It is to be hoped that a second skull 

 may be recovered. Thus far only the type skull and one addi- 

 tional lower jaw have been found ; hence, it is not possible to 

 add to the earlier descriptions except in wholly minor points 

 of interpretation. Moreover, abstracts of these descriptions 

 with figures are given in admirable form in Hay's work previ- 

 ously cited, a work which every student of the Testudinata must 



