ILLUSTRATIONS 



Figures 



Page 



FiQUKE 1. Diagrams illustrating structural conditions found in the sacral 



vertebra and coccyx of Mexican tailless amphibians 18 



2. Terminal phalanges of the toe in the foot of Hyla 18 



3. Diagrammatic ventral view of shoulder girdle of Bufo ameri- 



canus .- 27 



4. Lateral and dorsal views of Bufo alvarius from Guadalupe 



Canyon, Sonora, Mexico ._ 36 



5. Lateral and dorsal views of type specimen of Bufo canaliferus, 



from Tehuantepec, Oaxaca, Mexico 40 



6. Lateral and dorsal views of type specimen of Bufo coccifer, from 



Arriba, Costa Rica 41 



7. Lateral and dorsal views of Bufo cognatus from Nebraska 42 



8. Lateral and dorsal views of cotype specimen of Bufo compadilis 



from Pesquieria Grande, Nuevo Leon, Mexico 45 



9. Lateral and dorsal views of Bufo cristatus from Jalapa, Vera 



Cruz, Mexico 49 



10. Lateral and dorsal views of Bufo debilis from Delaware Creek, 



Culberson County, Tex .. 50 



11. Lateral and dorsal views of Bw/o mannws from Gatun, Panama. 54 



12. Lateral and dorsal views of Bufo marmoreus from mountains 12 



miles north of Santo Domingo, Oaxaca, Mexico 58 



13. Lateral and dorsal views of Bufo punctatus from La Paz, Lower 



California 61 



14. Lateral and dorsal views of Bufo simus from Valley of Mexico 



and from Dolores, Nayarit, Mexico 64 



15. Lateral and dorsal views of Bufo valliceps from Victoria, Tex.- 69 



16. Lateral and dorsal views of type specimen of Bufo woodhousii, 



from San Francisco Mountain, Ariz 73 



17. The T-shaped terminal phalanx of Me?^//ieroc/adt/iws 76 



18. Lateral and dorsal views of Engystomops pustulosus from Santo 



Domingo, Oaxaca, 'Mexico 79 



19. Fore feet of Central American liylids, illustrating the extent of 



the web between the fingers 141 



20. Hind feet of Mexican hylids, illustrating the extent of the web 



between the toes 141 



21. Diagrammatic ventral view of shoulder girdle of Rana cates- 



beiana 195 



22. Diagrammatic dorsal view of skull of Rana catesbeiana 196 



23. Diagrammatic ventral view of skull of Rana catesbeiana 196 



24. Opened mouth of Rana pipiens, showing position of vomerine 



teeth 204 



Pl/ATES 



Plate 1. Bufo alvarius Girard Frontispiece 



I? 



