. The Deseado formation of Patagonia . Palaeomastodon. The palatal bones are slenderin front, and broaden toward the rear, again, as in elephants. On the interior of the brain case is the cavity for thebrain which indicates that this organ was of diminutivesize, measuring about 150 mm, in length by 50 mm. inwidth at the widest part. It indicates a brain with verysmall cerebral hemispheres, which, however, had a swollenposterior margin, a larger cerebellum, and a wide medullaoblongata. The impression which I obtained of this brainis strikingly like that given for Palaeomastodon. On eitherside o
. The Deseado formation of Patagonia . Palaeomastodon. The palatal bones are slenderin front, and broaden toward the rear, again, as in elephants. On the interior of the brain case is the cavity for thebrain which indicates that this organ was of diminutivesize, measuring about 150 mm, in length by 50 mm. inwidth at the widest part. It indicates a brain with verysmall cerebral hemispheres, which, however, had a swollenposterior margin, a larger cerebellum, and a wide medullaoblongata. The impression which I obtained of this brainis strikingly like that given for Palaeomastodon. On eitherside of the brain cavity are a couple of vacuities, apparentlyfor lightening the weight of the skull. At the inner endof the auditory meatus is a large ear chamber, dividedinto a smaller anterior or cochlear portion, and into alarger posterior ear chamber proper. In figure 109, I have placed a diagram of the base ofthe skull of Pyrotherium, along beside that of Palaeomas-todon, for comparison of the basicranial foramena. The PYROTHRRIUM 169. Fig. 109. Palatal views of the basicranial region of A. Pyrotheriiim, and B. Palaeoniastodon, for comparisons; ale, alisphe-noidal canal; a/5., alisphenoid bone; Bsp., basisphenoid bone; eu., Eustachian canal;/./.m., foramen lacerum medium;/././>.,foramen lacerum posterior; , foramen ovale; , foramen for the internal common carotid; mx., maxilla; , occipitalforamen; pal., palatine bone; , post-palatal foramen; pt., pterygoid bone; , and , post-tympanic process ofthe squamosum; sq., squamosum; , stylomastoid foramen. 170 THE DESRAD(3 FORMATION OF PATAGONIA skull of Palaeomastodon is somewhat more elongated,especially in the posterior part. In both, there are twoantorbital foramena; the postpalatal foramena of Pyro-therimn arc a trifle further back, but this palatal region inboth is of the same type which is peculiar to elei)hanlsand Pyrotherium. In Pyrolhermm the condylar foramenis separate, while in elep
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Keywords: ., bookcentury1900, bookdecade1910, bookpub, booksubjectpaleontology
