G. R. Wieland — Upper Cretaceous Turtles. 115 



of costals, the first pair being large and overlapping the inner 

 ends of marginals 1-4 ; the second and third of nearly the same 

 area, width, and length as the second and third vertebrals. 

 Unlike the 1st, the 2d-4th costals lie entirely on the pleuralia. 

 Plastron. — Of medium size, the length being two-thirds, 

 and the least width of the bridge one-fourth that of the cara- 

 pace. Anterior and posterior borders not emarginate, but 

 slightly truncate or " abbreviated." Very heavy, and united 

 to the carapace by sutures (cleidosternal union), with the 

 strong axial and inguinal buttresses meeting respectively the 

 3d and the 8th marginalia. Composed of 9 heavy bony plates 

 all strongly united by suture, with the narrow line-like furrows 

 marking the borders of the twenty horny shields distinct. 



(a) The Bony Plates : There are the usual eight paired 

 plastrals with a rather large entoplastron of sub-hexagonal out- 

 line, and completely enclosed by the epi- and hyoplastra. The 

 heavy axial buttress extends forward to the posterior portion 

 only of the inner edge of the third marginal, and the large 

 inguinal buttress (peduncle) backward to the anterior portion 

 of the inner border of the 8th marginal. The inferior inner 

 borders of these and the intervening 4th, 5th and 6th and 7th 

 marginals pass well in to meet the plastral elements, and the 

 bridge is firmly anchylosed. 



(b) The Horn Shields : Intergular separated by a furrow or 

 semi-divided into paired parts ; gulars of sub-isosceles triangu- 

 lar outline ; numerals meeting on a straight mesial line ; but 

 pectorals, ventrals, femorals and anals on an irregularly sinu- 

 ous line crossing and recrossing the median sutural junction 

 of the bony elements beneath ; three paired inframarginals, 

 axial, mesial and inguinal, with an indistinct small fourth pair 

 well down in the humeral notch. All outlines indicated by 

 fine lines or narrow grooves. 



Adocus imnctatus a Distinct Species. 



In his original description Professor Marsh stated that the 

 present type was most like A. beatus of Leidy, and the iden- 

 tity of these species has since been claimed by several. I find 

 however, on comparing the figures of Leidy's type,* that spe- 

 cific differences are to be made out even from the fragmentary 

 materials which constitute it. To make these clear, I show in 

 figure 2 (a and b) the first left marginals of the forms in ques- 

 tion. They are not of the same proportion, nor are the verte- 

 bral and marginal horn shields of so nearly the same outline 



as they would normally be in one and the same species. 

 # * # # * •* * 



* Leidy, Cretaceous Eeptiles of the United States (Philadelphia, 1865), 

 Plate XVIII, figures 1-3. 



