178 University of California Publications in Zoology [Vol. 27 
egg complement of halophilus to be as much as 10,000. The present 
writer has measured the total spawn of one mated pair of toads from 
Lafayette which was isolated and which spawned in captivity on April 
19, 1922. The total volume of the spawn was 325 cubic centimeters. 
A sample of 26.5 cubic centimeters contained 1351 eggs by actual 
count, so the total mass was calculated to contain about 16,500 eggs. 
These figures are much larger than those given by Wright (1914, 
p. 32) for Bufo americanus at Ithaca, New r York. 
The eggs of this species are deposited in long slender strings of 
jelly (pi. 14, fig. 43), circular in cross-section. These strands are 
extruded (in pairs) intermittently over a period of some hours (5 
hours in the case of one captive pair, 8 hours with another), and 
when spawned in pools or creeks containing aquatic vegetation the 
movement of the toads here and there in the water while laying is in 
progress results in the egg strands being woven about the vegetation. 
An individual egg string of Bufo boreas halophilus measures 4.89 
to 5.29 millimeters in outside diameter. There is an outer cylindrical 
sheath, the walls of which are 1.35 to 1.45 millimeters in thickness. 
Within this is a cylindrical core 3.54 to 3.82 millimeters in diameter 
and in this the eggs are held, in two, occasionally three, lengthwise 
rows. Individual eggs measure 1.65 to 1.70 millimeters in diameter. 
The vitelline capsule is close about the egg, measuring only 1.70 to 
1.75 millimeters in diameter (fig. X). The jelly, when freshly laid 
and swollen to normal size, is as clear as that on any of the eggs of 
the water-spawning amphibians of central California. I failed to find 
segmentation in the inner core such as is shown by Wright (1914, 
p. 17, fig. 1a) for Bufo americanus. The jelly in most natural loca- 
tions usually soon becomes coated with fine sediment. 
Embryonic development is rapid. One lot of eggs taken to the 
laboratory at Berkeley on April 15, 1912, was hatching on April 20. 
Another lot taken on April 19, 1922, kept in a small aquarium which 
received sun for only a portion of each day, hatched out about 
April 28. In the field, especially in the interior valleys and in south- 
ern California, hatching probably occurs in a shorter period. 
At my request Mr. Philip N. Baxter kept track of the stock of 
Bufo boreas halophilus in a pool at Stockton, San Joaquin County, 
during the late spring of 1922. Collections were made at short inter- 
vals during April and May. The following table, based on this 
material, shows the increase in size in the general population with 
the advance of the season. 
