1901.] IIEPTILES FROM PATAGONIA. 183 



Cretaceous period \ It is also known that the mud-fish Geratodus, 

 which now survives in Queensland rivers and once lived in 

 Patagonia'", belongs to a race which was cosmopolitan in the Jurassic 

 period. In these two cases, Australia and South America ai-e 

 proved to be merely remote refuges for old types which have been 

 lost by extinction elsewhere. It is therefore just possible that, if 

 the direct ancestors of Jliolania were known, this remarkable 

 Chelonian would prove to have originated not on any old Antarctic 

 continent, , but in some other region of the globe from which 

 scattered survivors vvandered into the lands now named South 

 America and Australia respectively. 



EXPLANATION OF THE PLATES. 



Plate XV. 



Miolania arffentina(pTp. 170-172); cranium, upper aspect, one-third nat. 

 size. — From Eed Sandstone, Chubut, Argentine Eepublic. oco., 

 occipital crest ; orl>., orbit ; r.-v., bony bosses. 



Plate XVI. 



Miolania, argcntina (p. 172) ; same cranium, lower aspect, one-third nat. 

 size. 5s., basispbenoid ; i.^zf., interpterygoid vacuity ; oi<., otic bones ; 

 f.na., palato-nares ; ^i'., pterygoid ; /■., palatal ridge; s.occ, supra- 

 occipital ; other letters as above. 



Plate XVII. 



Fig. 1. Miolania argentina (^. 171); same cranium with imperfect mandible, 

 right lateral aspect, one-half nat. size, au., auditory opening ; na., 

 anterior nares ; s., hinder limit of horny beak ; other letters as 

 above. 

 1 a. Ditto ; oral aspect of mandible, one-half nat. size. 



Plate XVIII. 



Fig. 1. Miolania argentina (p. 173) ; right scapula, imperfect proximally, one- 

 half nat. size, t., tuberosity. 



2. Ditto ; bony ring of tail-sheath, posterior and right lateral (2 a) aspects, 



one-third nat. size. 



3. Genyodectes serus (p. 179) ; preuiaxillse, anterior aspect, one-half nat. 



size. — From Eed Sandstone, Chubut. 



Plate XIX. 



Fig. 1. Genyodectes serus (p. 179) ; imperfect jaws, right lateral aspect, one-half 

 nat. size, d., dentary ; ma\, maxilla; p^nx., premaxilla. 

 la. Ditto; two mandibular teeth of same specimen in position, inner 

 aspect, nat. size, d., dentary ; spl., anterior splenial extension. 



1 A. Smith Woodward, Catalogue of Fossil Fishes in the British Museum, 

 pt. iv. (1901), pp. 140-144. 



2 F. Ameghino, Sinopsis Geologico-Paleoucoiogica— bupiem. (l»yy), p. iU. 



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