238 THE AMERICAN NATURALIST. (VoL; XXXIII. 
produced. It is even possible, in consideration of the marked 
nocturnal habits of this species, that the female may leave the 
egg-mass during the night, returning to it by day. 7 
Comparison of the Eggs. —The comparative size of the eggs 
of the two species is shown in Figs. 3 and 4, in which they are 
drawn five times the natural size. Each appears protected by 
three membranes, two that fit closely and an outer loose one. 
It is by means of strings proceeding from this latter that the 
one is attached to the parent and the other to the surface of 
the stone, although in the latter case there appears to bea 
. definite adhesion, in which not only the stringy processes but 
also the surface of the membrane itself participates. As the 
development shows, the egg of Spelerpes is holoblastic, like 
the more usual amphibian egg, while that of Desmognathus is 
meroblastic. 
Development of Spelerpes. — Figs. 5-19 represent a series of 
views illustrative of the external development of Spelerpes and 
drawn to the same scale (x5). As the eggs used in these 
observations were of several different ages, it was not easy for 
me to fix definite time-limits to the several stages. 
The oldest eggs collected were almost at Stage d when found. 
Stages a-d rest upon observations made upon the youngest lot 
collected ; e-# are consecutive stages of the oldest lot. As I 
have the dates of the stages figured, the record is complete, 
except for the time between d-e, which may be from 24-48 
hours, The record, compiled from my notes, is as follows :— 
Stages a and b. The youngest eggs collected May 27, at 10 
A.M., showed no visible traces of external folds. Their appear- 
ance 24 hours afterward (10 A.M., May 28) is represented in 
Figs. 5-9. The development was somewhat uneven, and Stages 
a and 4 were selected as the extremes. 
Stage c. These were drawn from the same lot as a and b, 
six hours afterward, May 28, 4.10 p.m. (Figs. 10, 1 I.) 
Stage d. Killed May 29, 12.20 m. (Figs. 12, 13.) 
Stage e. These are from another and more advanced batch 
of eggs. All the other stages are taken from this lot. 
The specimens of Stage e, as figured here (Figs. 14-16), were 
killed May 28, 4 p.m. The time it takes Stage d to reach the 
