SPECIAL WORK. 
Mamm. 35 
C. fTYPOTHERIJDiE, 
Ameghino, F. Observaciones sobre algunas Especies de los Geperos 
^Typotherium y Entelomorphus. Rev. Arg. Hist. Nat. i, pp, 433-437. 
Mainly deals with the question of the number of species ; but also 
shows that Typotherium ranges from the Pleistocene Patnpean beds to 
the Mid. Tertiaries (Miocene) of Monte Hermosa and Catamarca, 
Mercerat, A. Apuntes sobre el G^nero Typotherium. Rev. Mus. la 
Plata, ii, pp. 74 et seq. 
Criticizes Ameghino’s species of this genus. 
t Typotherium studeri , n. sp., Moreno & Mercerat, Rev. Mus, la Plata, i, 
p. 228, Mid. Tertiary, Catamarca. 
t Typotherium internum, n. sp., Ameghino, Rev. Arg- Hist. Nat. i, 
p. 93, ibid. 
Hegetotherium convexum , p. 133, f anceps, fcuneatum, -fcostatum, 
p. 242, Low, Tertiary, Patagonia, Ameghino, Rev. Arg. Hist. Nat. i : 
n. spp. 
t Xotodon crisiatus, n. sp., Moreno & Mercerat, t, c ., p. 228, Mid. 
Tertiary, Catamarca. 
Y \Palceolithops , n. n.,to replace Ijithops , J.887, preoccupied ; Ameghino, 
Rev. Arg. Hist. Nat. i, p. 240. 
v HTremacyllus , n. g,, Ameghino, t. c, p, 241 ; type, Pachyrucus 
impressus 3 Amegh, 
d. fToxouoNTipj;. 
t Mercerat, A, Sinopsis de la Familia de los Protoxodontidce. La 
Plata : 1891, 8vo, 68 pp. 
Includes a large number of so-called new forms, most of which are 
identified in the following paper by Ameghino with those previously 
described. 
Ameghino., F, Nesodontidce. Rev, Arg. Hist, Nat. i, pp. 354-379, figs. 
After noticing the above memoir by Mercerat, the author makes some 
very important additions to our knowledge of Nesodon, It is shown that 
there is an enormous difference between the milk and permanent den- 
tition, which has been the source of many errors. In the first place it is 
shown that Owen’s N. sullivani is merely the adult of N. imbricatus ; and 
that his N. ovinus belongs to Adinolherium. The genera Colpodon 3 Pro- 
toxodon 3 Adelphotherium, Atrypotherium , ap4 .Scopotherium are then 
severally identified with Nesodon , their type species mostly helonging 
to N. imbricatus . The paper concludes with a synopsis q>f the species of 
Nesodon aud the allied genera, among which several are recorded as 
new. For a full monograph of Nesodon , see the memoir by Burmeister 
quoted on page 5, in which figures of the skull are given, and several of 
Ameghino’s genera are identified with Nesodon. 
