G. JR. Wieland — On Marine Turtles. 101 



The ulna is sliort and massive. The proximal articular sur- 

 face is slightly crescentic in general outline, and somewhat 

 concave except for an oblique, low, saddle-shaped ridge which 

 divides this face into sobequal areas, the larger facing towards 

 the radius. The distal articular surface is moderately convex 

 antero-posteriorlv, and rather flat in the dorso-ventral direc- 

 tion. The bone has a distinct broad and shallow grooving on 

 the proximal ventral, and on the distal anterior side, marking 

 the proximal and distal contact with the radius and producing 

 the effect of a marked twist corresponding to the high angle 

 between the general trend of the proximal and distal articular 

 faces. As in the case of the humerus and radius, there is a 

 certain correspondence with Dermoehelys, but the ulna of the 

 latter is more roujided. 



The intennediitm is much rounded and very robust. The 

 ulnars is suboval in external outline, with the proximal edge 

 much the thicker. The insiforni is very large, of subcrescen- 

 tic outline, thick, and quite flat, but with a raised border on 

 both faces. 



The carpalia and metacarpals present have more the appear- 

 ance seen in the Cheloninge than in Derinochelys^ in which 

 respect there is in fact a wide difference, the pronouncedly 

 marine appearance of the rounded subcylindrical and flat-ended 

 metacarpal and phalangal bones of the latter being quite 

 absent. 



General Resemblances. In so far as now known, the manus 

 and pes of Protostega and Archelon resemble those of Dermo- 

 chelys rather more than any other form. Briefly pointed out, 

 the more marked similarities of the manus are, the approxi- 

 mately equal length of the radius and ulna, the heavy proximal 

 bow of the radius, the carpal organization with the centrale 

 excluded from contact with carpale 1, and an enormous pisi- 

 form set high up near the ulna, and mainly on the ulnare. 

 The point of most importance and necessarily of the greatest 

 difficulty to settle with complete satisfaction is as to the 

 assumed contact of the centrale with carpale I. 



Professor AYilliston has, I think, omitted one of the tarsalia 

 from liis restoration of tlie hind limb of Protostega, so that 

 there is likewise an even closer general correspondence between 

 the hind limbs of these several forms than he suggests. The 

 diminution of the flfth finger of the hind flipper, as he shows, 

 to a single metatarsal is, I suppose, not to be regarded of as 

 much importance as any reorganization of the carpalia or 

 tarsalia (loc. cit.). 



