SCOTT: TOXODONTA OF THE SANTA CRUZ BEDS. 
233 
Measurements. 
Radius, distal width .... 
.041 
Metacarpal III, length 
.065 
“ thickness 
.028 
“ proximal width . 
.019 
Carpus, length in median line 
.030 
“ distal width of shaft . 
.0225 
width of proximal row . 
•043 
“ width of trochlea 
.016 
“ “ distal row 
•0445 
Metacarpal IV, proximal width . 
.016 
Metacarpal II, length. 
.060 
Phalanx I, digit II, length . 
.013 
“ proximal width . 
.017 
“ prox. width. 
.0145 
“ distal width of shaft . 
.0185 
Phalanx 2, “ “ length . 
.Oil 
“ width of trochlea 
.0115 
“ “ “ “ prox. width. 
.012 
Localities. — The type-specimen in the Ameghino collection is from Kar 
Aike. Nos. 9184 and 9532 were collected by Mr. Barnum Brown, the 
former 15 miles south of Monte Leon and the latter 5 miles north of 
Coy Inlet. 
Adinotherium karaikense (Ameghino). 
Acrotherium karaikense Amegh.; Rev. Argent, de Hist. Nat., T. I, 1891, 
p. 131. 
Nesodon imbricatus Lydekker; Anales del Mus. de La Plata, T. II, 1893, 
p. 26. 
This species, which is known only from the type-specimen, appears to 
be merely an Adinotherium with a supernumerary premolar, just as the 
so-called Acrotherium rusticum would seem to be an example of Nesodon 
imbricatus with an additional premolar, such as Bateson has noted in 
many recent mammals. That A. karaikense is specifically distinct is 
made extremely probable by the following facts: ( 1 ) In size, this species 
exceeds any other known example of the genus, the length of the skull, 
which in A. robustum is 27 cm., being 29 cm. (2) In proportion to its 
length, the skull is narrow, the zygomatic arches curving outwardly but 
little, which is in strong contrast to the broad head and greatly expanded 
arches of A. robustum. (3) The facial region narrows anteriorly much 
more gradually than in the latter. 
My photograph shows a pair of rough frontal ridges, which may or may 
not represent the horn-bosses ; it is difficult to determine this from the 
photograph. 
.Locality. — Kar Aike. 
