212 



G. R. Wieland — On Marine Turtles. 



dorsal line, especially the first seven, this grooving being deepest 

 and widest in the middle of each plate, from whence characteris- 

 tic surface striations radiate. Regarding the number of neuralia 

 I can only say that the boundaries of the first eight are distinct, 

 but to make out clearly the relations and proportions in the pygal 



Figure 1. — Archelon ischyros Wieland. The nuchal, the anterior margi- 

 nal border of the carapace, the neuralia, the pleuralia, and the complete rib 

 series, with the last cervical and the first dorsal centra. — Dorsal view with 

 nuchal set somewhat forward. (All the dorsal and sacral vertebrae are present 

 and articulated in their natural position in the type specimen, on which the 

 present figure is based, with the sole exception of the first rib.) 



One-twentieth natural size. 



region cannot now be readily done, in the absence of work by 

 a preparateur. The final median plate shown in the figure is 

 possibly represented as too long. Fortunately, however, the 

 fine specimens I have secured promise when fully elaborated to 



