The Peeper, Hyla pickeringii (Holbrook). 41 



recorded them arranged singly (Plate i, Fig. 2g), never in packets or 

 masses, as often occurs in restricted captive quarters, where sometimes 

 they are found in bunches of 4 to 12 eggs (Plate vii, Fig. 1). Neither 

 have we seen eggs attached to sticks, yet in captivity such material has 

 been used. Most of our field records of eggs were accidental. Seldom 

 do we find them when especially bent upon it. The outer envelopes 

 of peeper eggs (Text-figure Ic) range in diameter from 1.4 to 2.0 mm.; 

 average 1.7 nun.; mode 1.8 mm. The vitellus diameter ranges from 

 0.9 to 1.1 mm.; the average 1.0 mm.; the mode 1.0 mm. The vegeta- 

 tive pole is white or creamy white, never yellowish; the animal pole is 

 black or brownish. The egg of Hyla versicolor (Text-figure 1e) almost 

 invapabl}'' has an inner envelope, while the reverse is the general rule for 

 the egg of Hyla pickeringii (Text-figure Ic) . But if one should find the 

 latter egg with such an envelope, the two would not be difficult to dis- 

 tinguish. The inner envelope of the tree-toad egg would equal the 

 diameter of the outer envelope of the peeper egg. Furthermore, the 

 outer envelope of the tree-toad egg ranges from 4 to 6 mm. in diameter; 

 that of the peeper egg, from 1.4 to 2 mm. The outer envelope of the 

 tree-toad egg is loose in consistency and ragged on the outside; that of 

 the peeper egg is firmer and smooth on the exterior. The egg-comple- 

 ment (1,500 to 2,000) of the tree-toad is laid in small packets at the 

 water's surface from the last of May onward; each egg of the peeper's 

 complement (800 to 1,000) is laid singly, submerged, and usually before 

 the tree-toad has begun ovulation. 



THE HATCHING PERIOD. 



A mated pair captured on March 30, 1907, laid early on the morning 

 of March 31. On the morning of the 4th of April, 5 days after deposi- 

 tion, the eggs were hatched. A month later another pair laid in laboratory 

 and their ^gs, under a higher temperature, hatched in 4 days. The 

 eggs laid on the morning of April 29 began hatching on the morning 

 of May 3 and half of them were hatched by 3 p. m. of the same day. 

 Several attempts were made at placing egg-complements laid in labor- 

 atory^ in special hatching-trays in various ponds, but without success. 

 Finally on March 29, 1910, a pair was placed in a glass jar and this was 

 sunk in the pond of their capture, the wire-gauze top being on a level 

 with the water's surface. They began laying in this receptacle at 

 once. Fifteen days later came the first record of the eggs hatching. 

 During this period, the minimum water-temperatures ranged from 50 

 to 66 degrees; the maxima from 67 to 79 degrees. 



THE MATURE TADPOLE. 



Length of the body 1.4 to 2.1 in the length of the tail, average 1.65. 

 Width of the body in its own length 1.3 to 1.65, average 1.46.' Nostrils 

 twice nearer eye than the end of the snout. * Eye lateral, equidistant 

 from spiracle and snout. Distance between nostrils in interorbital 



