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. : 
Premolars not enlarged............+6 sa taraiaesveeieie ta saa 'ele are sawielawess Phenacodus. 
aa. Superior premolars with one external cusp, enlarged. 
Inferior fourth premolar with internal crest and cusp.......e.eeeeees Catathleus . 
Inferior fourth premolar without internal crest or cUSp........0:...44- Mioclenus. 
II. Superior premolars 1, 2 and 3 without inner lobe; third with three external 
lobes (Pictet). 
Premolars compressed.......ccceecncscaccccccsaacceeseeeseerenees Dichobune. 
In the genus Catath/eus the development of the premolars is 
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 m1 and Iv, but unites with 
it in the 11; it supports on the Iv, an anterior,a median and a 
posterior cusp, the latter forming part of the rather narrow heel. 
The true molars 1 and 1 have seven tubercles, the four principal 
ones, and three smaller, one anterior, one posterior, and one me- 
dian. On the third the posterior forms a large heel. All of the 
molars, but especially the premolars, have the enamel thrown into 
sharp parallel folds, in a manner I have not seen in any other 
mammal. Length ‘of six superior molars, .067; length of three 
true molars, .029; length of base of third ‘premolar, 012; width 
of do., .012; width of base of first true molar, .o1o0; do. of third 
true molor, .009; length of do.,.o10. Length of base of fourth 
inferior premolar, .012; width do., .o12; of third true molar, .orrs ; 
width of do.,.009. The teeth indicate an animal of the size of 
the peccary. 
Mioclenus turgidus, gen. et sp. nov. This genus differs from 
Catathleus in the greater simplicity of the structure of the infe- 
rior premolars, which are without internal crest or cusp. The in- 
ner lobe of the superior premolars is less developed than that 
genus. In the JZ turgidus the characters of Mioclenus are 
