350 BAUR. [Vol. IV. 



From what I have said above, some of these statements 

 have to be modified. I beheve also that what is called ligament 

 by Boulenger is really cartilage, and we would have, therefore, 

 in Platysternum, a cartilaginous mesogastroid separating ento- 

 pubes and entoischia. Boulenger does not mention the epigas- 

 troid and hypogastroid, but I conclude that these elements are 

 also present. 



The condition of the pelvis seen in the Pinnata can also be 

 derived from that in the Chelydridae. In the living Cheloniidae 

 ectopubes are far separated from the ectoischia, but are con- 

 nected by the mesogastroid cartilage, which perhaps in very old 

 specimens may become ligamentous. The epigastroid is pres- 

 ent, rounded in front, and may become calcified or ossified in 

 old specimens ; the hypoischium is reduced entirely. Even in 



Fig. 8. — Chelonia jnydas, L. 



E, Epigastroid. 

 M, Mesogastroid. 

 H, Hypogastroid. 



pretty large specimens (length of bony coracoid 255 mm.) the 

 gastroid cartilage is still continuous. Between the entopubes 

 it is visible from above, between the entoischia from below, be- 

 ing always placed on the sharp angle in which these elements 

 meet. In some fossil Cheloniidae, like Allopleuron, entopubes 

 and entoischia are nearer together. This leads to the condition 

 seen in the Dermochelyidas, in which entopubes and entoischia 

 seem to meet each other. I could not examine a fresh speci- 

 men of Dermochelys, and have to rely on Wagler's^ and Hoff- 

 mann's ^ figures, Gervais' ^ not being at hand. According to 

 these figures the entopubes seem to touch the entoischia, but 

 there is some uncertainty about it. In Hoffmann's figure the 

 left entopubis reaches the ischium, but the right one does not. 



1 Wagler, Job.: Natiirliches System der Amphibien, 1830, Pis. T, Figs. 21, 22. 



2 Hoffmann, C : Reptilien, in Bronn's Klassen und Ordnungen, Taf. XI, f. 3. 



3 Gervais, P. : Osteologie du Sphargis Luth., Nouv. Arch. Mus. VIH. Paris, 1872. 



