LIST OF ILLUSTRATIONS. 



PLATE I. 



FIG, 1. A typical breeding-place for bullfrogs. 



2. Hypothetical pond, showing form, distribution, and arrangement of Anuran 

 egg-complements. 



A. Green-frog. D. Tree-toad. G. Peeper. 



B. American Toad. E. Bullfrog. H. Wood-fro?;. 



C. Pickerel-frog. F. Meadow-frog. I. Swamp Cricket-frog. 



PLATE II. Normal embraces of local species studied. 



1. Mated pair of Bufo lentiginosus americanus. Axillary amplexation. XI. 



2. Mated pair of Rana sylvatica. Pectoral amplexation. XI. 



3. Mated pair of Rana palustris. Pectoral amplexation. XL 



4. Mated pair of Rana pipiens. Pectoral amplexation. XI. 



PLATE III. Hind feet (a) and fore feet (6) of breeding male Anura. XI. 



1. Rana sylvatica. 4. Rana clamata. 7. Hyla versicolor. 



2. Rana pipiens. 5. Chorophilus triseriatus. 8. Bufo lentiginosus americanus. 



3. Rana palustris. 6. Hyla pickeringii. 9. Rana catesbeiana. 



PLATE IV. 



1. Cross-embrace of a male Bufo lentiginosus americanus with a dead female 



Rana pipiens. The amplexation is pectoral, not axillary. X0.5 



2. Cross-embrace of a male Rana pipiens with a female Rana palustris. The pair 



captured in the field in a mated condition. X0.5. 



3. A female Rana pipiens showing the effects of 17 days' pectoral amplexation. XI. 



4. A mated pair of Rana pipiens showing the pectoral (Rana) type of amplex- 



ation. X0.75. 



5. A pair of male Hyla versicolor showing the axillary type of amplexation, where 



fingers are folded back in the embracing male. X0.75. 



6. A mated pair of Rana clamata, the small male holding axillary-like on the right 



side and partly pectoral-like on the left side. X0.5. 



PLATE V. Swamp cricket-frog (Chorophilus triseriatus). Photographs by A. A. Allen and 

 the author. 



1. A pair of swamp cricket-frogs. 4. The pair arising to the surface for air after 



2. A pair in position preparatory ovulation. 



to ovulation. 5. A mature tadpole. 



3. A mated pair in act of ovulation. 6. An egg-mass. 



PLATE VI. Egg-masses. 



1. Egg-masses of Rana sylvatica. Both masses are globular; the upper mass is 



not fully expanded. 



2. Egg-mass of Rana pipiens. Plinth-like, not globular, as in Figs. 1 and 4. 



3. Egg-mass of Chorophilug triseriatus. Several such bunches laid by one female. 



4. Egg-masses of Rana palustris. Globular mass, frequently in tiers. 



5. Egg-mass of Rana clamata. A surface film among vegetation. 



PLATE VII. Egg-masses. 



1. Eggs of Hyla pickeringii laid in the aquarium. 



2. Two egg-strings of Bufo lentiginosus americanus. A string from each oviduct. 



3. Egg-mass of Rana catesbeiana. A surface film, 18 inches in diameter, laid 



among dead sticks and old boards. 



4. A surface-packet of Hyla versicolor eggs attached to a Potamogeton leaf. 



PLATE VIII. Mouth-parts of mature tadpoles. X15. 



1. Rana catesbeiana. 4. Rana clamata. 7. Hyla pickeringii. 



2. Rana palustris. 5. Rana sylvatica. 8. Hyla versicolor. 



3. Rana pipiens. 6. Bufo lentiginosus americanua. 



PLATE IX. 



FIG. 1. Mature tadpoles. X 1. 



A. Rana catesbeiana, third season F. Rana palustris. 



(two years old). G. Rana clamata, first season (three 



B. Rana catesbeiana, first season to six months old) . 



(three to five months old). H. Hyla versicolor. 



C. Rana catesbeiana, second season I. Hyla pickeringii. 



(one year old). J. Rana sylvatica. 



D. Rana pipiens. K. Bufo lentiginosus americanus. 



E. Rana clamata, second season (one 



3'ear old). 



IV 



