438 OLIVER p. HAY 



there is abundant room for humerals, gulars, and even intergu- 

 lars. The last-mentioned two pairs of scutes are apphed to the 

 epiplastra and the front of the entoplastron, as may be seen in 

 figures of the Pleurosternidae and Baenidae (Hay, Fossil Tur- 

 tles of N. A., 1908). These bones in Triassochelys were evidently 

 small, and the gulars and intergulars were correspondingly small. 

 To the writer it seems quite probable that the front of the plas- 

 tron of Jaekel's specimen broke off along the humeropectoral 

 sulcus. 



Doctor Jaekel tells us (p. 106, fig. 9) that in his Triassochelys 

 there are on each side of the carapace seventeen peripheral 

 bones and that the marginal scutes correspond to these in num- 

 ber and in their boundaries. These are statements of such 

 importance scientifically that they ought to be supported by un- 

 questionable evidence. Although Doctor Jaekel states that these 

 peripherals are very distinctly set off from each other and from 

 the costals, he does not say that the bone sutures are present. 

 Unless the sutures are to be seen, the limits of the bones are 

 indeterminable. The condition of the shell in general indicates 

 that the sutures are closed. What sets the areas off from one 

 another is probably only the sulci between the marginal scutes. 

 Indeed, Jaekel (p. 199, fig. 23) informs us that such is the case. 

 If the reader will examine the figures in the writer's work of 

 1908, referred to above, which illustrate the structure of the 

 Baenidae (apparently not distant relatives of Triassochelys), 

 or will take a look at a shell of one of the Chelydridae or a shell 

 of Chelys, he will find that the sulci between the marginal scutes 

 cross the borders of the carapace at the notches, while the 

 bone sutures cross between the notches. In the Baenidae there 

 are often some small apparently supernumerary scutes at the 

 front of the carapace. These appear to correspond to the little 

 scutes which Doctor Jaekel has counted as the first and second 

 in his series. At the rear of the carapace of Baena the supracau- 

 dal scutes have been suppressed, along with the pygal bone. 

 In Triassochelys these supracaudal scutes are present, but much 

 reduced in size. In this way we may account for the unusual 

 number of marginal scutes in Triassochelys. In that animal 



