334 LOWER VERTEBRATES. 



"During this brief interval these animals spawned, the eggs being attached to 

 blades of grass and slender twigs. These eggs hatched on the 2d of July, and a 

 large series were gathered a week later. To return to the eggs. During the time 

 that intervened from the laying of the eggs untU I gathered specimens of the tad- 

 poles, there occurred four moderately heavy showers, so that the water in the sink- 

 hole at no time disappeared, but was much below the level that it reached during the 

 protracted rainfall of June 26. Very much, therefore, of the spawn that was laid 

 was high and dry for from two to four days before hatching, and I suppose was 

 destroyed. 



" On the evening of July 9, I found the water in the sink-hole confined to a few 

 very shallow pools of limited area, and in these pools were a few hundreds of Scaphi- 

 opus tadpoles. In comparison with the abundance of eggs seen June 26, and of 

 young seen a week later, it is evident that a large portion of the eggs was destroyed, 

 and a vast number of very young tadpoles were killed by the soaking away of the 

 water. 



" I have never known any like disparity between the eggs of frogs or common toads, 

 and the young in the tadpole state ; and it is at once very evident that if the spade- 

 foot toads habitually or usually deposit their eggs in temporary pools, then we have 

 an obvious reason for tlie positive rarity of the animal, as apparently it is the rule, 

 rather than the exception, for the egg to be destroyed or the young perish. 



"The tadpoles gathered July 9, which were then seven dajs old, were curious 

 creatures. At this time the hind legs were well developed, although small, and did 

 not interfere with the animals' natatorial locomotion. The bodies of these young 

 Scaphiopi were short, stout, and oval, and, when viewed in the water, deep velvety 

 black ; but when closely examined it was found that the two irregularly parallel 

 yellow dorsal stripes, that are so prominent a feature in the coloration of the adult 

 male, were plainly discernible. 



" The movements of these tadpoles were not different from that of the young frogs 

 and toads in this stage of their existence. Those that I had in an aquarium moved in 

 companies, as though following a leader, and occasionally one would drop out of the 

 ranks, come quickly to the surface, eject a bubble of air, and dive again quickly to 

 the bottom of the tank. Like all tadpoles they had enormous appetites, and when 

 fed with bits of raw meat quickly attached their sucking mouths to the food offered, 

 and did not remove them, I think, while a particle of blood remained in the mass. 



" A week later, July 16, the majority of these tadpoles had acquired their front 

 legs, and the tail had perceptibly diminished in size, but still was used by them when 

 moving through the water. At this time, however, the movements of the animal 

 are far less active than before or soon after, and for a few days, if exposed to the 

 attacks of any enemies, would suffer far more than at any other period of their lives. 



"A very curious feature in the growth of these animals is now to be noticed. Of 

 the specimens I had under examination in an aquarium, about five per cent did not 

 progress beyond the condition which all were in July 9. These 'retarded' tadpoles 

 proved to be voracious cannibals. They seized their more matured companions by 

 their tails and legs, swallowing the member, and thus sustained their own lives at the 

 expense of their fellows. They generally killed their victim in the course of twenty- 

 four hours, and often in less time, and then promptly seized another. So blood- 

 thirsty were these few 'retarded' tadpoles, that I was compelled to protect the lives 

 of the little hoppers, their brethren, which now, in spite of stumps of tails, sat in 



