43 



backward a suture extended for the union of the last marginal and the pygal bone. The 

 surface of the neural and the suprapygal is raised medially into a low, rounded, 

 longitudinal ridge. 



No very decided sculpture is shown on the surface of the bones. Striations occur 

 adjoining and at right angles to the suttires ; elsewhere there is a slight roughness in 

 places, more particularly toward the vertebral ends of the costals, which on close 

 examination is seen to be produced by small, obscure and irregular depressions separated 

 by very faint ridges. Comparatively large, concentrically curved groove-like markings 

 also occur on two of the costals. 



The great development of the last neural by apparent coalescence with a suprapygal, 

 the resulting compression of the pygal region and the addition of a 9th pair of bones to 

 the series of costals, form a combination of characters that is both interesting and uniqiie. 



A new genus is here proposed for this Mid-Cretaceous type that is thought to show 

 gTeater affinity to the Chelydridcp. than to any other groujp. 



Belly River series, Red Deer river, 1901. 



PLEUROSTERNIDJ]:. 

 Baena, Leidy. 



BAiJNA HATCHERI, Hay. 



Ba^nahatcheri,^&j. 1901. Annals 

 of the Carnegie Museum, pp. 325-.326) 

 plate XV. " Description of a new species 

 of Baena (B. hatcheri) from the Laramie 

 beds of Wyoming." 



This species is represented 

 from the Cretaceous of Red Deer 

 river by a specimen, fig. 8, in 

 which the whole of the plastron is 

 preserved with the anterior half of 

 the carapace. The sutures between 

 the bones are well defined and the t 

 sulci are distinct. The carapace 

 has suffered slightly from distor- 

 tion, but the plastron is admirably 

 preserved leaving little doubt as to 

 the specific identity of the Red 

 Deer river turtle with the Wyo- 

 ming type. 



Fig. 8. — The plastron of Baena hatcheri ; from 

 Red Deer river. One-half natural size. 

 /&',Intergular shield ; G, Gular do. ; 



HUM, Humeral do. ; PEC, Pectoral do. ; AB, Abdominal do. ; FEM, Femoral do. ; AN, Anal do. : ep, Epi- 

 plastral bone ; entp, Entoplastral do. ; hyp, Hyoplastral do. ; msp, Mesoplastral do. ; hpp, Hypoplastral do. ; xp, 

 Xiphiplastral do. ; * centre of front margin of carapace. 



