X I-IST OF ILLUSTRATIONS 



Synopsis and oEscniPTioN of North American tadpoles 



By A. H. Wright 



Facing page 



1-5. Mouth parts of North American tadpoles 70 



6-9. Lateral aspects of live tadpoles 70 



New fo.ssil mollusks from the Miocene of Virginia and North 

 Carolina, with a brief outline of the divisions of the 

 Chesapeake group 



By Wendell C. Mansfield 



1-5. New fossil moUusks from the Chesapeake group 12 



The fossil crinoid genus Vasocrinus Lyon 



By Edwin Kirk 



1-2. Species of fossil crinoid genus Vasocri7ius 16 



New fresh-water and marine bivalve shells from Brazil and 



Uruguay 



By William B. Marshall 

 1-4. Bivalve shells from Brazil and Uruguay 8 



Bathmopterus, a new fossil ga.steropod genus from the Silu- 

 rian OF Alaska 



By Edwin Kirk 

 1. A new fossil gasteropod from the Silurian of Alaska 4 



A NEW species of trichostrongylid worm of the genus Coope- 



RIA from the CARABAO IN THE PHILIPPINE ISLANDS, WITH A 

 review of the GENUS 



By Benjamin Schwartz 

 1. Cooperia nodidosa, new species 6 



Mineralogy and geology of Cerro Mercado, Durango, Mexico 

 By William F. Foshag 



1. Cerro Mercado from the south, the bold outcrops and iron ore 28 



2. Views of Cerro Mercado 28 



3. Breccia partially replaced by diopside 28 



4. Breccia partially replaced by calcite and magnetite 28 



The gums of the porpoise Phoccenoides dalli (True) 

 By Gerrit S. Miller, jr. 



1. Teeth of a Phocaena and b Phocoenoides . 4 



2. Jaws of Phocoenoides 4 



3. Gums of Phocoenoides, lower jaw 4 



4. Gums of Phocoenoides, upper jaw 4 



