BATRACHIA. 335 



froglike fashion on their haunches, and were in all respects miniatures of the adult 

 spade-foots that in April and June made night hideous with their unearthly cries. 



"Having tested several specimens, a few days j)revious]y, as to their ability to 

 assume the land-life of adult Scaphiopi, by placing them upon damp sand, and finding 

 that they throve fairly well, on the 25th of July I removed the water in the aquarium 

 and put in earth to about an inch in depth, and very carefully smoothed the surface. 

 Upon this the young spade-foots were placed, and in less than one minute many had 

 commenced digging little burrows, into which they disappeared as the excavations 

 deepened. In all respects these burrows were like those made by adult spade-foots, 

 oval in outline, oblique in direction, and generally with the slight angle in the course. 



" In twenty minutes all but two, of forty-four specimens, were below the surface of 

 the earth stratum I had placed in the aquarium. 



" During this simple series of observations of young Scaphiopi in confinement, I 

 watched also the development of those left in the sink-hole. The water there soon 

 was confined to mere puddles concealed in the dead leaves, and before the young had 

 their limbs fully developed, the depth was nowhere sufiicient to permit of swimming. 

 Three days in advance of the maturing of my confined specimens, T saw, in a sink- 

 hole, a few individuals which had fairly assumed the land-living, air-breathing stage of 

 existence. Supposing that, like those I had at home, they would burrow in the earth 

 where they were, I did not visit the locality from the 21st to the 31st of July, on 

 which date I made an exhaustive but unsuccessful search for them. Not a trace of 

 either young or adult could I discover. It cannot be said that they were overlooked. 

 My search was too careful and comprehensive for this, and I believe that these sjiade- 

 foots, both old and young, wander farther from their breeding grounds than is sup- 

 posed, or else dig far deeper into the earth than a depth of six or eight inches, as 

 stated by Holbrook and De Kay." 



The Hylid^, or true tree-toads, embrace one hundred and seventy-five species, of 

 which by far the greater number inhabit tropical America. About twenty species 

 inhabit Australasia, one species tropical Asia, and one, the Syla arborea, extends from 

 western Europe to Japan. The ball and claw-like character of the terminal phalanges 

 of the toes of the members of this family have been already referred to. There are 

 dwellers in trees found in other families, especially in the Cystignathidse and the 

 Ranidse, all of which have fiat or disc-like dilatations on the extremities of their toes, 

 like those of the Hylidae. But the shape of the supporting phalange is different in 

 each case. In the Hylodes type of Cystignathidse it is T-shaped, and in the Ranidse it 

 is generally Y-shaped. In some members of the Hylidae the chai-acters are not A-ery 

 well presented, especially in the North American genera ChoropMlus and Acris, 

 which live on the ground, frequently in the neighborhood of water. Some of the 

 species of the typical genus Hyla have similar habits, and approach those genera in 

 structure, viz., the Hyla pickeringii of North America. Among the arboreal types 

 there is a great range in the ossification of the skull, as I have already shown to be the 

 case in other families. In Hypsiboas and Hyla there is a large cranial fontanelle, 

 while in Trachycephalus the extensive cranial ossification occupies the skin, so 

 that the head is bared and rough on its upper surfaces. This forms an excel- 

 lent protection against snakes. In the genus Triprion this ossification is carried to a 

 great degree. It forms a pi'ominent rim overhanging the mouth all round, projecting 

 in front like the brim of a cap in one species, the T. petasatus of Yucatan, or like 

 a spoon in another, T. spatulatus of West Mexico. This genus is also entirely 



