112 G. R. Wieland — Upper Cretaceous Turtles. 



Art. IX. — Structure of the Zipper Cretaceous Turtles of New 

 Jersey: Adocus, Osteopygis, and Propleura / by G. R. 

 Wieland. (With Plates I-IX.) 



One of the most striking geologic features of New Jersey 

 is the area of Upper Cretaceous Greensand or "Marl" which 

 extends obliquely across the state from the Delaware Bay to 

 Sandy Hook. Few Mesozoic formations yield a richer series 

 of extinct vertebrates ; and amongst these, the Testudinates, as 

 here so well represented by marine, littoral, and doubtless land 

 forms, are of great interest and importance from a biologic 

 point of view. 



These turtles mainly occur in the "Greensand" with the bones 

 of birds, pterodactyls, dinosaurs, crocodiles, mosasaurs, gigantic 

 fishes, and sharks, not many feet below a prominent and exten- 

 sive bed of Gryphseas, preceded and followed by marls. There 

 are implied' abruptly changing conditions and a near shore; 

 and there is a constant likelihood that there may here be found 

 primitive •marine or littoral turtles presenting characters allied 

 to those of the old stocks from which the original marine, turtles 

 were derived, a fact which needless to say gives to the investi- 

 gation of the specimens from the Greensand an exceptional 

 value. For amongst the fundamental skeletal changes exhibited 

 by extinct forms, none are more interesting than those connected 

 with the evolution of flippers. Moreover the manner in which 

 this took place in the turtles is rapidly nearing very complete 

 demonstration. As yet, however, the structure of the Upper 

 Cretaceous turtles of New Jersey has received but brief atten- 

 tion. 



The carapace of Adocus as figured by Professor Marsh 

 some years since, has made this the best known of these 

 forms. But with this exception the descriptions and figures so 

 far as given have been based on fragmentary material, and 

 there has been little evidence presented as to the character of 

 the limbs. Nevertheless the sand matrix, and the naturally 

 disarticulated and uncrushed condition of the skeletal elements 

 of these fossils (see Plate IX), afford the opportunity for rarely 

 satisfactory study. In the following initial descriptions a more 

 adequate knowledge of three of the genera is for the first time 

 made available. 



I. Adocus punctatus Marsh. — (With Plates I-IV.) 



The genus Adocus was first assigned by Cope* to some frag- 

 mentary remains from the Upper Cretaceous or Greensand of 

 New Jersey, these having been originally described by Leidy 



* Proceedings of the Academy of Natural Sciences, Philadelphia, 1868. 



