WIELAND : THE OSTEOLOGY OF PROTOSTEGA 291 
themselves be quite clear upon this point were it left unnoticed. The ilia are of 
course shown in the lateral view; this, as the result of compression, being the only 
view remaining in fairly exact proportion. 
Similarly the left fibula, as shown in Plate II., is turned partly around with a 
portion of the plastron adhering, the facet for contact with the distal end of the 
tibia being thus directed upwards. There can be but the barest doubt that the posi- 
tion of all the elements of the hind flippers as assigned in the accompanying Fig. 
5 is correct. The presence of paired parts afforded a means of so exactly checking 
ACA peas 
This; 
(hi Wh i 
lif 
U 
WY 
Mi 
Waly 
i jf 
Fic. 5. Protosteya gigas. Right pelvic girdle and flipper. ><+. The dorsal or ectal view of flipper with the corre- 
sponding ental view of the pelvic elements show in the plane of the paper. P, pubis; F, fibula; ¢, tibiale intermedium 
and centrale fused, or caleano-astragalar element ; 1-3, first to third tarsalia ; 4, fourth and fifth tarsalia fused ; m, meta- 
tarsal 1; p, phalanx 1; I.—V., first to fifth toes and ungual phalanges. 
the determinations as to exclude all possibility of error. Moreover, nearly all the 
parts, save perhaps the two ulnares, were imbedded in their matrix in a closely 
articulated natural position. And it should be noted that the tibiale, all the tarsalia, 
and the first metatarsal and some of the phalanges of both flippers remain so articulated, 
the evidence as to their position hence being incontestable. Also metatarsal V., 
though not articulated, or otherwise joined by remaining matrix, is of such char- 
acteristic form as would testify amply to its position, even though isolated. ‘The 
same may be said of metatarsal 1. The development is in both cases much the 
same as in all the marine turtles. Unfortunately, however, no element referable to 
a fibulare, which appears to have been present, is now determinable. Nor is a 
