Hay: Tuktm-s from iiif. Iidiih Rinkr 15ki)S. 



179 



broken away. It has had a thickness of about 6 mm. and in section 

 the edge has been rounded. The third and the fifth and sixth costals 

 have been much thickened to receive the buttresses of the plastron. 

 The second costal, near its proximal end, has a thickness of 5 mm ; 

 the fourth, near its distal end, a thickness of 3 mm. 



The surface of the carapace presents evidences of a low ridge along 

 the midline. On the area of the first costal scute there is a low 

 elongated boss. In front of this, on the first perijjheral, there is 



Flo. I. Baena callosa Hay. Diagram of portion of carapace, -^^j^ natural size, 

 vert.sc, vertebral scute ; cost.sc, costal scute. 



another and smaller boss. Probably a complete carapace will show 

 these to form the anterior ends of two lateral carina. 



The carapacial scutes (Fig. i) have been separated by very dis- 

 tinct sulci. The first vertebral scute has been small, having a length 

 of probably less than 30 mm. and a width of 60 mm. The second 

 vertebral is 48 mm. long and 75 mm. wide; the third vertebral 57 

 mm. long and 65 mm. wide. The fourth has been fully as wide as 

 the third. The first costal scute is small, being about 36 mm. in 

 antero-posterior extent. 



