ON THE OSTEOLOGY AND RELATIONSHIPS ‘OF 
PROTOSTEGA. 
E. €. CASE. 
INTRODUCTION. 
THE systematic arrangement of the sea turtles, or Pzzxata, 
has long been a mooted point among zodlogists. Prior to the 
year 1870 there was practical unanimity in placing Dermochelys 
near the members of the Chelonzidae. In the year 1871 Cope 
(1) separated these forms, and placed Dermochelys in a distinct 
group, Athecae, opposed to and of equal rank with the Cryptodira 
and Pleurodiva. One year later, in discussing the genus 
Protostega (2) he placed it ‘near the Sphargidae in the sub- 
order Athecae, and in some points to be approximated to the 
Cheloniidae.”’ In 1875 he established the family Protostegidae 
(3), a name he had used two years earlier (4). 
The group Athecae was apparently accepted by Gervais in 
his description of Dermochelys (Sphargis) (5), and the separa- 
tion of the group was recognized by Seeley (6), who in 1880 
placed Dermochelys in a group Dermatochelyidae, of equal rank 
and value with two opposing groups, Peltochelytdae and 
Aspidochelyidae. 
Doderlein (7) accepted Cope’s classification with the addition 
of the group 7vionychotdea, and this group was subsequently 
adopted by Cope (11). Bottger (29) in 1895 recognized the 
Athecae. LDollo (8) in 1886 published a paper in which he 
raised the value of Cope’s group Azkecae by placing it in oppo- 
sition to all the remaining Zestudines grouped under the name 
Thecophora. This idea he subsequently defended in two papers 
which appeared in 1887 (9) and 1888 (10). 
Dollo was supported by Smith-Woodward (12), Bernard (18), 
and by Boulenger, both alone (13) and in collaboration with 
Giinther (14). These later authors substituted, as did Lydekker, 
(15, 16) the name Zestudinata for Dollo’s Thecophora. 
