1883,] 313 [Cope. 
and O. corrugatus ; and very probably, O. ferow. The position of the dz. 
protogonioides, M. baldwint and IM mandibularis is uncertain, though the 
last two are probably Oxyclent. 
The Mioclenus cuspidatus is distinguished among its congeners, by the 
transverse character of its superior molar teeth, that is, by the relatively 
smaller anteroposterior diameter as compared with the transverse ; and by 
the prominence and acuteness of their principal cusps. They thus stand 
at the opposite extreme of the genus from the M. turgidus, where the teeth 
are characterized by the robustness and obtuseness of the cusps, although 
in the triangular basis of the second superior molar they agree. The ex- 
ternal cusps are compressed cones, and in contact at the base; the inter- 
mediate tubercles are small and distinct. The internal cusp is large and 
prominent. The base of the fourth premolar is T-shaped, and is as long 
as wide. Its internal and external cusps are well developed. The cingu- 
lum of the true molars is complete all round on the last one, and on the 
two others except at the internal base, where it is interrupted. The second 
molar only displays a posterior inner tubercle of the cingulum, which is 
small, and does not give a truncate interior outline of the crown, charac- 
teristic of M. opisthacus, M. ferow, etc. On the ms. i and ii, the cingulum is 
expanded at the external angles of the crown, most so anteriorly. The an- 
terior expansion rises in a low cusp in the P-m, iv. The enamel is smooth. 
This species need only be compared with M. opisthacus and M. subtri- 
gonus, which are of about the same size. Passing by the differences 
already mentioned in the table, the fourth premolar has a different form 
from that of the M opisthacus. Inthe latter it is narrower and more trans- 
verse, and with larger conical cusps, much as in AZ. turgidus ; in the pres- 
ent species it has the trilobate outline seen in JZ subtrigonus. As to the 
latter species, the tecth are wide, and the cusps smaller and separated 
at the base, and the cingulum is crenate and lobate, in a manner quite 
different from the smoothness and compactness of structure seen in the 
M. cuspidatus. 
Measurements. M. 
Length cf base of last four superior molars..........++: .026 
hy “hi CCH POS TIME MMONUTE Viny ibe ee ¥ Meme be, VOLO 
. A ATVOTOPOBLOTION os sles sates sewn sOO8 
Diameters of P-m. iv 4 anteroposters 
WE MBVOLEOU Te Vcc das Wesau sce ys | 1008 
. 2 
Diameters of mm. {. j anteroposterior - 
AHIR EN SOC Vii d: aicheupia-dnd Sev oes nimiala: On UUID 
Diameters of m. iid QUGROPOSLONION sss cscesesisvenne O0GE 
LUMA OMG rl epeiescoinrectny es OUR 
Diameters of m. wid EUTLOBODORTOTION,S «sss tu ous sya s moe OO 
transverse...... CEN SRA CREAM AO 
D. Baldwin, discoverer. 
Curracus TRUNCATUS, Sp. nov, 
The genus Chriacus m. was characterized in the Proc ceedings of the 
PROC, AMER. PHTLOS, 800. XxI. 114. 2N. PRINTED JANUARY 17, 1884. 
