VERTEBRATE PALiEONTOLOGY IN 1910 689 



of lateral expansions of the spines of the vertebrae, with over- 

 lying intercalated dermal plates. Cleithrum very large and 

 expanded above. Clavicles small, without external pittings. 

 Interclavicle smooth on the dermal surface, small, with a 

 short posterior process. Humerus without ectepicondylar 

 process. 



In the typical Dissorophus the carapace occupies the full 

 width of the body, with a broad and elongated shield in front 

 overlying several vertebrae ; but in Cacops it is only slightly 

 broader than the vertebrae, becomes narrower in front, and is 

 not fused into an anterior dorsal shield. 



In reference to Cacops, Mr. Williston observes that "the 

 creature, as mounted, presents an almost absurd appearance, 

 with its large head and pectoral region, absence of neck, and 

 short tail. It is certain that it possessed no other dermal 

 ossifications than those of the median dorsal carapace, anci it 

 would seem almost as certain that the creature was aquatic 

 or largely amphibious in its habits. Almost frog-like in 

 appearance, it doubtless had more or less frog-like habits. 

 What was the significance of the dorsal carapace I am at a 

 loss to suggest. That it could have been a protection seems 

 more than doubtful, whatever may have been its use in 

 Dissorophus ; but this coincidence is remarkable : with an 

 external turtle-like ear-opening, it had also the beginning of 

 a turtle-like carapace. And this parallelism is also seen in 

 Diadectes, a reptile with dorsal dermal plates and turtle-like 

 ears. . . . That the animal was a swimmer I do not doubt, 

 and in all probability the feet were webbed — they were certainly 

 not clawed. Whatever may have been its habits, the creature, 

 with the nearly related Dissorophus, must be classed among the 

 oddities of vertebrate palaeontology." 



In a paper on reptiles and amphibians from the Permian of 

 Texas, published in Bull. Amer. Mus. Nat. Hist, vol. xxviii. 

 pp. 163-88, Mr. E. C. Case gives a restoration of the skeleton of 

 the cotylosaurian genus Diadectes. These reptiles appear to 

 have been sluggish, harmless and perhaps burrowing in their 

 habits, carrying the body close to the ground. A special sub- 

 order, Gymnarthria, is suggested for the new genus Gymnarthrus. 

 Several new amphibians are named. In a second paper. I.e. 

 pp. 183-88, the same writer describes, under the name of 

 Poecilospondylus francisi, a new genus and species of pelyco- 



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