262 PATAGONIAN EXPEDITIONS : PAL/EONTOLOGY. 



? Pseud hapalops Lydekker, in part ; Anales del Mus. de La Plata ; T. Ill, 



1894, p. 100. 



This genus is very closely allied to Hapalops and should perhaps be 

 united with it ; for the present, however, it will be preferable to keep it 

 distinct, because of the lack of transitional specimens. The only diagnos- 

 tic character of Hyperleptus is the peculiar shape of the premaxillae, which 

 form short, broad, triangular plates, with the apex directed forward ; the 

 change is due to the relatively great broadening of the postero-external 

 branch of each premaxillary, whereby the incisive foramina are reduced to 

 very narrow slits ; the surfaces on the maxillaries for articulation with the 

 premaxillae are also characteristic. The preorbital fossae are very deep, 

 producing a marked constriction of the palate at the diastema between 

 - and -, while the alveoli of the upper caniniform teeth are so prominent 

 as to produce a strikingly broad muzzle, much as in Rucholczops. The 

 postero-external opening of the dental canal (external dental foramen) is 

 on the horizontal ramus at the base of the coronoid. 



HYPERLEPTUS GARZONIANUS Ameghino. 



(Plate LIV, Figs, i, 10.) 



Hyperleptus garzonianus Amegh. ; Rev. Argent, de Hist. Nat., T. I, 



1891, p. 155. 



? Euchofaops fissognatkus Amegh. ; Ibid. p. 323. 

 ? Hyperleptus schissognathus Amegh. ; Enum. Synopt. des Mamm. Foss. 



de Patagonie, 1894, p. 152. 

 ? EiicJwlceops litoralis Amegh.; Rev. Argent, de Hist. Nat, T. I, 1891, 



p. 322. 

 ? Hyperleptus litoralis Amegh. ; Enum. Synopt. des Mamm. Foss. de 



Patagonie, 1894, p. 152. 

 f Pseud I lap atop s ntetimeyeri Lydekker, in part ; Anales des Mus. de La 



Plata, T. Ill, 1894, p. 101. 



The type-specimen in the Ameghino collection has been considerably 

 altered in appearance by lateral compression, which renders the skull un- 

 duly narrow and exaggerates the apparent development of the sagittal 

 crest. 



The teeth display but few differences from those of Hapalops ; the 

 upper caniniform (-) is of moderate size and subcylindrical shape ; it is 

 implanted a very short distance behind the anterior border of the max- 



