830 General Notes. [ October, 
Tetraconodon Falc. and Lydd., in the enlarged proportions of their 
premolar teeth. I compare the genera as follows: 
I. Third and fourth superior premolars one or two-lobed externally, and with 
internal lobes, 
a. Superior premolars with two external lobes; inferior fourth with two median 
cusps. 
PPR WOlATS NOt ONIBIIAd s b clea o sine Mped oie de anand aus eepe ak Phenacodus. 
Superior premolars with one external cusp, enlarged. 
Inferior fourth premolar with internal crest and cusp......e+.-+eeee Catathleus . 
Inferior fourth premolar without internal crest or cusp......... eee Mioclenus. 
Superior premolars 1, 2 and 3 without inner lobe; third with three externa} 
lobes (Pictet). 
CP OTN ae ec ecb aesbee caine ses ba ves cewhe bet eut Dichobune. 
In the genus Catath/eus the development of the premolars 1s 
remarkable, while the true molars are relatively small. The last 
three superior premolars have an elevated internal crescentic cin- 
gulum, homologous with the inner lobe of the fourth superior 
premolar of the ruminants. The general character of the true 
molars is that of Phenacodus. Parts of two or three individuals 
of this species have come into my possession, one of which in- 
cludes nearly all of the molar dentition of both jaws. The exter- 
nal cusp of the superior premolars is compressed conic, and the 
internal cingulum extends to its anterior base in the second, third, 
and fourth, The crown of the last true molar is about as long aS 
wide, while that of the first is wider than long. Each supports 
seven cusps ; two subconic external; one large median internal, 
which is connected by ridges with a small anterior and posterior 
median. Then there.are a small anterior and posterior internal, 
making three internal. The internal crest is distinct from the 
principal cusp in the inferior premolars 111 and Iv, but unites with 
it in the 11; it supports on the 1v, an anterior,a median and a 
posterior cusp, the latter forming part of the rather narrow heel. 
true molor, .009; length of do., .o10. Length of base of fourth 
inferior premolar, .012; width do., .012; of third true molar, .O! 15 ¢ 
width of do., 009. The teeth indicate an animal of the size © 
the peccary, 
Mioclenus turgidus, gen. et sp. nov. This genus differs ee 
Catathleus in the greater simplicity of the structure of the inle- 
rior premolars, which are without internal crest or cusp. “and 
ner lobe of the superior premolars is less developed ae pa 
genus. In the MM. turgidus the characters of Mioclenu 
