ON THE PHYLOGENY OF THE CARAPACE, ETC. 799 
the Upper Cretaceous, Wieland ?* found a complete series of eleven 
epineural elements (fig. 5, Hp) covering the much reduced real neurals 
and probably continuous in front over the nuchal. These elements 
correspond with the larger of bony scutes in the neural keel in the 
Leatherback (fig. 1). 
Fig. 4. Diagram of the Carapace of Toxochelys bauri Wieland, lateral view ; about 
4 nat. size. After Wieland, 1905, p. 330, text fig. 3, from Menger. Epithecal 
elements black, thecal elements dotted. 
Ep, epineurals; Mg, marginals; Nu, nuchal; S.py, suprapygals. 
3. In Archelon ischyros again Wieland?*® discovered two more 
anomalous elements, obviously also epithecal. One element is free, 
the other united by its jagged edge with a typical marginal element, 
indicating the presence of a supramarginal row of epithecal elements 
(fig. 5, Smg); the jagged border of the marginals also points to the 
presence of such a series of elements. 
Fig. 5. Diagram of the Carapace of Archelon ischyros Wieland, dorsal view ; about 
7s nat. size. After Wieland, 1909, p. 114, fig. 7, from Menger, somewhat modified. 
Epithecal elements black, thecal elements dotted. 
Ep, epineurals ; mg, marginals ; Nu, nuchal; Smg, supramarginal. 
4. The same turtle is obviously in the possession of typical mar- 
ginal bony plates. Now, since these marginals are of the same 
character as the one supramarginal discovered in this animal, obviously 
lying in the same layer and possessing the same jagged edges (fig. 5, 
28 1909, p. 115. 29 1909, p. 120. 
