AMPHIBIANS—GOIN 433 
to the caecilians, there are no special modifications known of either 
the larvae or the oviduct to permit this change in life history. 
Sirenidae.—The aquatic sirens have been reported time and time 
again to exhibit external fertilization, but these reports have been 
based on the fact that no one has yet demonstrated either the produc- 
tion of spermatophores by the male or the presence of a receptacle for 
storing the sperm in the cloaca of the female. Nonetheless, I am not 
yet convinced that the Sirenidae practice external fertilization. In 
Pseudobranchus, the dwarf siren, the eggs are deposited singly on the 
roots of water hyacinths and are so widely scattered that often an en- 
tire afternoon’s collecting will produce less than a dozen eggs. They 
may be spaced as much as 5 or 10 feet apart. Dissection of mature fe- 
males readily demonstrates that they may have well over 100 eggs 
ready for deposition at one time. It seems inconceivable that such a 
large number of widely scattered eggs could be fertilized externally. 
The eggs hatch several weeks after deposition, but of course the young 
larvae never metamorphose because these, like Vecturus, are aquatic 
forms that retain the gills. Since in both the Hynobiidae and the 
Cryptobranchidae, the two families of salamanders that are known to 
have external fertilization, the eggs are laid in clusters, either in little 
capsules or packages, or in rosarylike strings, it would seem that the 
habit of spacing the eggs at wide intervals would be unique among 
salamanders with external fertilization if the Sirenidae are, in fact, 
really salamanders—but that is another story. 
Leiopelmidae.—These primitive frogs have internal fertilization 
with the “tail” (cloacal appendage) of the male acting as a copulatory 
structure. In the tailed frog, Ascaphus, the voiceless male swims 
about on the bottom of a flowing stream until he finds a female. He 
grabs her and secures a firm grip, clasping her just in front of her 
hind legs and humping his body so as to bring his extended cloacal 
appendage into position to thrust into her cloaca. The sperm is ap- 
parently transported to the female cloaca by means of this appendage. 
The eggs are deposited in coils of rosarylike strings which adhere to 
rocks at the bottom of the stream. In the cold water in which these 
eggs are deposited, embryonic development is slow, and transforma- 
tion does not occur until the following summer. The only close rela- 
tive of Ascaphus is Leiopelma of New Zealand. This frog has been 
reported to lay eggs on land which go through direct development, 
but the details of mating and method of egg deposition are unknown. 
Pelobatidae.—As in other families, there is a good deal of variation 
of life histories in the burrowing toads. The reproductive pattern of 
the spadefoot toad, Scaphiopus h. holbrooki, is somewhat typical of 
the New World forms in that there is a speeding up of the develop- 
mental processes in correlation with the habit of breeding in tem- 
porary waters. In torrential rains and hurricanes any time of the 
