PYROTHERIUM 163 
Pyrotheriidae Ameghino 
All the forms assigned to this family are supposed to be 
closely related to Pyrothertum and to have much the same 
structure. Ameghino has proposed the following genera, 
Pyrotherium, Parapyrotherium, Richardowenia, Archaeolo- 
phus, Propyrotherium. 
Parapyrotherium is based on a small molar and a tush 
which Ameghino first described as Pyrotherium planum, 
later elevating the species to a genus, designated as Para- 
pyrotherium, differentiated by the transverse crests being 
low and the valley at either end being blocked by an 
intertubercular ridge. (Gaudry considered that this genus 
represented either the milk teeth of P. romer?, or a variation 
of that species. I can not see the basis of a new genus in 
the material. 
The genus Richardoweni is based on half of a molar, 
which has the transverse crest interrupted in the middle. 
Too little is known of this form to base a valid genus or 
even to associate it with Pyrotherium. 
Archaeolophus is founded on a small tush and part of 
an upper molar, also inadequate material for a genus. 
It is probably Pyrotherium. 
Propyrotherium is a smaller form from the Astraponotus 
beds, apparently a good genus; the type species being 
P. saxeum, of considerable smaller size than any of the 
Deseado species. The distinctive features of the genus 
can not be given until more material is known. 
Carlozitielt is based on a small form from the Casamayor 
with narrow molars. An incisiform tush is associated with 
the molar, which, if correctly associated, would indicate 
a wide deviation from Pyrotherium, and would probably 
be an ancestral form. A second species is reported from 
the lower Deseado beds, but I am a little skeptical as to 
the horizon. 
