1914] The Egg-Laying Habits of Plethodon Cinereus. 125 



supply of nourishment for the female during her wait by the eggs. 

 Occasionally it will almost equal the remaining eggs in size and then 

 will be laid along with them, producing a cluster with one markedly 

 small egg. For example, in one cluster of seven eggs, six of them had 

 a diameter of 3.75 m.m., the remaining one of 2.75 m.m. From a 

 difference so marked as this there is a gradual transition to the state 

 where all the eggs of the cluster are the same size; such are about one 

 half of all cases. The writer has twice found similarly undersized eggs 

 of Ambly stoma; the numbers were small, nine and eleven in the two 

 cases, and the eggs of but two-thirds the normal size. They developed 

 normally, producing under-sized larvae which were perfect anatomically 

 but defective in their feeding instincts. The one lot would not feed 

 at all; the other would snap fitfully at Cyclops, etc., but would not 

 eat enough to grow or even to maintain life. This was quite striking 

 for both lots were the species jeffersonianum the larvae of which are 

 normally voracious feeders and easy to raise. In Plethodon the early 

 development of the small egg is quite normal, its fate has never been 

 followed past the time when the larva is well formed. 



One female, kept in a terrarium with her eggs, swallowed two of them, 

 and three hours later regurgitated them. The eggs were killed by the 

 process, whether by digestive action or by the mechanical violence it is 

 impossible to say, for they were in the process of gastrulation at the time. 

 This is a most critical period for the egg, its delicacy is at the maximum 

 and very slight disturbance will cause its death. The swallowing of 

 their spawn has been noted for many amphibia, usually where, as above, 

 something has happened to pervert the natural instincts. Smith (1907) 

 however, describes it as normal for Cryptobranchus; in this case more- 

 over when regurgitated the eggs frequently continue to develop. 



Means taken to determine the mating habits have so far been fruitless. 

 The single observation of Wilder (191 3) on Desmognathus is probably 

 a close approximation to the habits of Plethodon in this respect. 



