320 



PROCEEDINGS OF THE \ \TH>\ I/. \ll si:i l/. 



vol. 38. 



Table ofmeasurerm nts. 



mi asured. 



.1 . snl ^Ir kin 

 reduced 



Length of anterior lobe 



Width of anterior lobe 



Thickness of edge nearfronl 



Length ofentoplastron 



\v idth of entoplasl ron 



Width of bridge 



Length of posterior lobe 



Width of posterior lobe 



Contact of hyoplastral bones 



Contact of hypoplastral bones 



i ontacl oi hyo and hypoplastral bones taken together 



b "i" Intergular sulcus 



Combined width ofintergulars 



Length of interhumeral sulcus 



Length of interpectoral sulcus 



Length of interabdominal sulms 



Length of interfemoral sulcus 



Length of Interanal sulcus 



The anterior Lobe is rounded in front, without appearance of 

 epiplastral lip. [ts free borders arc subacute. Seen from above, 

 the bones thicken from this edge, until at about 15 mm. from the 

 edge they have a thickness of from 7 to 9 mm. The upper surface 

 of the lobe is nearly flat. The buttresses, anterior and posterior, 

 are little developed. The entoplastron differs from that of A. sub- 

 stricta in being somewhat pointed behind, instead of rounded or 

 subtruncated. It is longer than that of A. substricta in the ratio of 

 51 to 46, and narrower in the ratio of 71 to 76. It will be observed 

 that there is a union of the left hyoplastron with the right hypoplastron 

 and a similar connection between the hitter bone and the left xiphi- 

 plastron. Such irregularities are probably only individual pecu- 

 liarities, but similar ones are quite common among the ancient turtles. 



It is seen that the hyoplastra and the hypoplastic are shorter than 

 in A. substricta, relatively to the length of the anterior lobe. The 

 bridge, too. is shorter. The free border of the hinder lobe is somewhat 

 less acute than that of the anterior lobe. At the hypo-xiphiplastral 

 -lit tire the bones are 9 mm. thick. On the midline, 30 mm. behind 

 the suture just mentioned, the thickness is only 7 mm. The free 

 borders of the xiphiplastrals posteriorly are acute. On the upper 

 surface of each xiphiplastral there is a crescentic elevation for attach- 

 ment of t he pubic bone. 



The lower surface of the plastron is very indistinctly sculptured. 



The appearance i- as if there were rows of small pits, as in Adocus; 

 but th<\ are so faintly impressed thai they are hardly to be detected. 

 h will be seen I hat many of the horny scutes had very irregular 

 boundaries. Especially the median sulcus runs a very tortuous 

 com-.,.. The gular and intergular scutes differ little from those of 

 .1. substricta. The humero-pectoral sulcus crosses the hinder border 



