Scaphiopus holhrookii 97 



mm., 1.6, 1.6, 1.6, 1.8 mm. for vitelli and 3.8,4.0,4.0,4.0, 4.5 for envelopes. 

 A third group had 1.4, 1.6, 1.6 mm. for viteHi and 4.0, 4.0, 4.2 mm. for 

 envelopes. 



On three other lots the writer secured the following: One set give 1.4, 1.6, 

 1.6, 1.7, 1.8 mm. for vitelH and 4.2, 4.6, 5.4, 5.5, 5.6 mm. for envelopes. 

 Another group where egg envelope a day old or not fresh, tended to be ellip- 

 tical, we had vitelli 1.5, 1.7, 1.7, 1.7, 1.7, 2.0 mm. and envelopes 4.0, 4.1, 4.4, 

 4.5, 4.5 mm. The third group were one day or a little less old when pre- 

 served and jelly was more or less merged or there was no regularity of envelope 

 outline at all. At times an egg would hang at the end of a jelly cylinder as if 

 stalked with an egg in the end like a stalked egg — somewhat as occurs in egg 

 masses of Scaphiopus hammondii. 



At this writing (Dec, 1928) the fresh eggs of Aug. 16, 1922, now pre- 

 served in formalin surely look to be cream colored below and brown above. 

 Another accession of some fresh laid eggs in deeper water have the eggs ap- 

 pearing blackish. Furthermore, these eggs were preserved when mass was 

 still in the band form, the jelly unexpanded. Each band is from 4-6 eggs 

 wide. The width of some of these bands ranges from 5-8 mm. in breadth. 



Dangers. Dr. Abbott emphasizes this point. "During this brief interval 

 these animals spawned, the eggs being attached to blades of grass and slender 

 twigs. These eggs hatched on the 2nd of July and a larger series were gath- 

 ered a week later. 



'To return to the eggs. During the time that intervened from the laying 

 of the eggs until I gathered specimens of the tadpoles, there occurred four 

 moderately heavy showers, so that the water in the sink-hole at no time dis- 

 appeared, but was much below the level that it reached during the protracted 

 rainfall of June 26. Very much, therefore, of the spawn that was laid was 

 high and dry for from two to four days before hatching, and I suppose was 

 destroyed. 



"On the evening of July 9 I found the water in the sink-hole confined to a 

 very few shallow pools of limited area, and in these pools were a few hundreds 

 of Scaphiopus tadpoles. In comparison with the abundance of eggs seen 

 June 26, and of young seen a week later, it is evident that a large portion of 

 the eggs were destroyed and a vast number of very young tadpoles were killed 

 by the soaking away of the water. 



"I have never known any like disparity between the ages of frogs or com- 

 mon toads and the young in the tadpole state ; and it is at once very evident 

 that if the spade-foot habitually or usually deposit their eggs in temporary 

 pools, then we have an obvious reason for the positive rarity of the animal, 

 as apparently it iis the rule, rather than the exception, for the egg to be de- 

 stroyed or the young perish." 



The eggs usually hatch before the water evaporates enough to do damage 

 except to the bunches which are near the shifting borders of these transient 

 pools. Few are infertile. A few masses so appeared and one mass we tried 

 to hatch so proved. 



