1 882.] Geology and Paleontology. 853 



exceeds that of any of the species of this group. The apex of 

 the median V is not very prominent. Third superior premolar 

 with a rudiment of the anterior and posterior basal lobes ; inter- 

 nal lobe not large, conic. Fourth not wider than first true molar, 

 which equals the second and exceeds the third in size. An ex- 

 ternal cingulum on the true molars, none on the premolars. 

 Probable inferior true molars with anterior and posterior median 

 cusplets. Length of base of four last molars, .020 ; width of 

 base of P-m. in .006; length of do., .005 , do. of P-m. iv, .008 ; 

 length of do., .007. Diameters of M. ii, anteroposterior, .005 ; 

 transverse, .ooqS. From the Lowest Puerco. D. Baldwin.—/?. 

 D. Cope. 



Some new forms from the Puerco Eocene.— Miochinius pro- 

 togonioides, sp. nov. The largest species of the genus, represented 

 by the superior true molars. It is an exaggerated form of the 

 M. subtrigomts. The internal angle of the V, as well as the inter- 

 mediate tubercles at the ends of its limbs, are distinct. Cingula 

 extending entirely round the crown, the posterior with a small 

 tubercle on the M. 11 as in A. subtrigonus ; none on M. in, which 

 is .75 the area of the M. n. Diameters M. II, anteroposterior, 

 •008; transverse, .010. Diameters M. in, anteroposterior, .007, 

 transverse, .009. From the Lowest Puerco of New Mexico, D. 

 Baldwin. 



mioclarms opisthacus, sp. nov. — The species of this genus 

 brought thus far from the Puerco formation have no internal 

 cusp, but a ridge on the internal side of the heel of the inferior 

 true molar teeth. The J/. brachyst<>mus of the Wasatch has such 

 a cusp. The present species from the Puerco also possesses this 

 cusp. It differs from the M. brachystomus in its much larger size 

 and more robust premolars. The latter are. however, less robust 

 than in M. turgidus and have an oval anteroposterior section. 

 The fourth has a small heel, but no anterior basal lobe. The 

 true molars are of subequal size and not smaller than the premo- 

 lars. No anterior inner nor posterior median cusps. Length of 

 last four molars, .025 ; do. of P-m. iv, .006; of last true molar, 

 •°^5- Depth of ramus at M. n, .01 16. Three individuals. 



Mwchenus baldwini, sp. nov.— The description of the last spe- 

 c »es applies to this one in many respects, including the posterior 

 inner lobe of the inferior true molars, but the size is less, and the 

 last inferior molar is materially smaller. There is also a well de- 

 nned anterior internal cusp on the second true molar. The 

 ramus becomes quite slender anteriorly. Length of last six 

 molars, .035 ; do. of last four, .022 ; do. of P-m. iv, .0057; do. of 

 fr ». °053 ; do. of M. in, .0055. Dedicated to D. Baldwin, the 

 discoverer of the Puerco fauna. 



Protogonia plicifera, sp. nov. — This, the second species of the 

 genus, differs from its congener, P. subquadrata, in that the inter- 



