

No. 428.] DIEM YCTYLUS VIRIDESCENS 645 

Cope ('89) in his work on Batrachia describes a series of 
three to four pits along the sides of the head just back of the 
eye; he regards these as not constant for the species (Fig. 1). 
After examining a considerable number of animals I have 
come to the conclusion that these pits are constant structures. 
In adult males there are usually three to four quite large, deep 
pits, which can be seen without difficulty extending from just 
back of the eye along the side of the head. In adult females, as 
a general thing, one would say there are no pits, but on a more 
careful examination one to four small depressions are often seen ; 
these usually appear as pin pricks, or minute depressions in 
the skin. They are similar in structure to 
thosefound in the adult males, but are much 
smaller and less developed in the female. 
In early larval forms there are no signs 
of depressions or pits in either males or Ak its 
females, but in medium-sized to large red ge i E d Diediyc: 
males there are along the sides of the head T ii O ER ud 
minute depressions which look very much 
like those found in the adult females, and more or less advanced, 
according to the size of the animal. 
In early red females, as a usual thing, no pits are found, 
but in later red forms small beginning pits are sometimes 
present and sometimes absent ; but judging from all the indi- 
viduals examined it may be stated that as a usual thing these 
small pits of the female make their appearance at about the 
time the red land form changes to the viridescent water form, 
and that the corresponding structures in the male make their 
appearance in the small red forms about the time that their 
sex can be determined by dissection. 
Before speaking of the significance of these structures which 
are so well developed in the adult male and so rudimentary in 
the female and young, it will be necessary to speak somewhat 
further of the mating habits. Usually in captivity during the 
fall, winter, and spring the male at once settles upon the 
female’s back and clasps her just in front of her fore legs with 
his powerful back legs in such a manner that it is impossible 
for her to escape and, at the same time, possible for him to 


