1886. ] Geology and Paleontology. 451 
geology. Itis scarcely adapted for use in this country, though 
valuable for reference. The illustrations are mainly of European 
fossils, and the treatment is rather meager and dry compared with 
the other portions of the book; the classification adopted is in 
some points not fresh, and the entire treatment is not what is now 
wanted. . 
The Lophyton linneanum is figured as though it were a plant; 
the Ceratiocaris is still referred to the phyllopod Crustacea; the 
Tunicata are still retained with the brachiopods in that myste- 
rious collection called “ Molluscoidea.” These, however, are 
slight defects. But paleontology cannot be set forth in its truest 
ight by one who has not done practical work in biology and 
paleontology. 
70: 
GENERAL NOTES. 
GEOLOGY AND PALAIONTOLOGY. 
THE PLAGIAULACIDÆ oF THE PuERco Epocu.— Three species 
of this marsupial family have been thus far detected in the beds 
of the Puerco. These are Ptilodus medievus Cope, Vol. 1m, 
ES 
1885, 493; Neoplagiaulax americanus Cope, AMER. NATURALIST, 
1885, p. 493. Of these the last-named species is the largest, 
the lower jaws representing an animal of the probable size of 
ae rat, now able to add a fourth species to this 
list in a second species of Neoplagiaulax, much larger than the 
- americanus, and hence the largest species of the family 
- It is established on an entire inferior fourth premolar. 
The length of the base of this tooth is one third greater than 
that of the corresponding tooth of the N. americanus, and there 
are fifteen keel-crests on the side of the crown, while there 
are but seven in the N. americanus, The outline of the crown 
iS of the elongate and moderately convex character of that of 
the N. americanus, and thus not so elevated as in our species a 
of Ptilodus. The irregularity in the outline of the base of the 
Pemex, which was no doubt descended from the Plagiaulaci cide. 
call the animal Neoplagiaulax molestus—E. D. Cope. ote : 
l OF THE GEOLOGICAL FORMATIONS OF SPITZBERGEN.”— 
€ article with the above title, printed in the last D ber 
| Bumber of the American NATURALIST from a manuscript which 
Pee 
