
gi2 The American Naturalist. [October, 
evolution of the teeth. Chalicotherium shows a diplarthrous condition 
of both carpus and tarsus and no fibulo-calcaneal facet; there is no 
third trochanter ; the anterior intermediate cusps of the upper molars 
(protoconule) is reduced. 
We shall remain in the dark as to the truth of this suggestion until 
we find the complete feet of Meniscotherium. In the meantime the 
striking resemblances seen in the teeth point strongly towards a distant 
relationship between these forms.—HrEnry F, Osporn, American 
Museum of Natural History, New York, August 27th, 1891. 
The Family of Astrapotheriidz.—Senor Alcides Mercerat has 
recently published a paper on the Astrapotheriidz, to which he refers 
two’ new genera, Listriotherium and Xylotherium, as well as Bur- 
meister’s genus, Astrapotherium. Listriotherium is represented by two 
new species: Z. patagonicum Merc., from the Eocene of Monte Leon, 
and Z. filholii Merc., from the Eocene of Santa Cruz, Xylotherium 
has but one representative, X. miradile Merc., also from the Eocene of 
Santa Cruz. To Astrapotherium belong A. patagonicum Burm., A. 
augustidens Merc. sp. nov., A. marshii Merc. sp. nov., A. gaudryi 
Merc. sp. nov., all from the Eocene of Mt. Leon, Patagonia; also A. - 
magnum Owen, A. burmetsterii Merc. sp nov., A. robustum Merc. sp. 
nov., from Santa Cruz, Patagonia, and A. voghtii Merc. sp. nov., from 
the Eocene of Chubut. (Extr. Rev. Mus, de la Plata, Tomo I.) 
On a Skullof the Equus excelsus Leidy, from the Equus 
Bed of Texas.—I have received from my valued correspondent, 
William Taylor, a skull of the Æguus excelsus, which is of much 
interest as the first that has come to light in the United States. It 
lacks only the posterior and inferior walls of the brain-case, and the 
premaxillary region was detached in such a way that its length is not 
absolutely certain, though contact of the adherent matrix was found. 
This skull shows that the Æguus excelsus is intermediate in characters 
between the horse and the quagga and allied species, and possesses 
some Hippidium characters in addition. The resemblance is, how- 
ever, greater to the quagga. This is shown by the shortness 
of the premaxillary region, the abbreviation of the maxillary 
posterior to the last molar, and the long excavation of the posterior 
nares, which extends to the line of the anterior border of the penul- 
timate superior molar, It differs from both of these species in the 
posterior prolongation of the vomer over the presphenoid, and in the 
small size of the last superior molar. The latter tooth is smaller than 


