432 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1959 
ing toward terrestrial adaptation. In the red salamanders, Pseudo- 
triton, the eggs are deposited in small groups hanging from tiny root- 
lets and other submerged structures in cool, muddy springs. The 
female stays with the eggs, but apparently when they have hatched 
the larvae range for themselves. The dusky salamander, Desmog- 
nathus fuscus, on the other hand, lays its eggs not in the water but 
on land. They are deposited in small, grapelike clusters in shallow 
excavations in the soft earth, among bits of sphagnum, or under- 
neath stones or logs. These excavations generally are within a few 
feet of the water. Upon hatching the young salamanders do not go 
at once to the water, but remain for a week or two on land and show 
definite terrestrial adaptations. The posterior limbs are longer in 
proportion to the trunk region than at any time during later develop- 
ment. Likewise the tail lacks a fin. In short, this young salamander 
is not merely a little larva which has not yet had a chance to reach 
the water but is basically a terrestrial salamander, able to move about 
in the damp crannies and crevices leading from the nest to the nearest 
pool or stream. After about 2 weeks these young terrestrial larvae 
take up an aquatic existence until such time as metamorphosis occurs, 
which it usually does when they are about 7 to 9 months of age. 
Plethodon cinereus, the red-backed salamander of the eastern United 
States, exemplifies the typical terrestrial plethodontid life history. 
The female lays 3 to 12 large unpigmented eggs in crannies and holes 
in rotten logs. Each egg adheres firmly to those previously laid, so 
that a little mass of eggs seemingly enclosed in a single envelope is 
formed. The egg cluster is usually attached to the roof of the cavity. 
The embryos develop rapidly and soon exhibit well-developed external 
gills. These, however, are lost on hatching. The young emerge in 
the same form as adults and never take up an aquatic larval exist- 
ence. Finally, Zydromantes and Oedipus retain the eggs in the ovi- 
ducts and give birth to fully transformed young. 
Proteidae—This family, which includes the well-known mud 
puppy, Vecturus, is somewhat isolated structurally from the other 
salamanders and its members never completely metamorphose. Fer- 
tilization is internal. The female of Nectwrus maculosus lays eggs 
singly in still water and attaches them to the undersurface of rocks, 
boards, or other objects, usually in water 3 to 5 feet deep and from 
50 to 100 feet from shore in shallow lakes, although they have been 
recorded from streams. There are from 18 to 180 eggs in each clutch. 
They hatch after 4 or 5 weeks. In this genus there is, of course, no 
metamorphosis, since these salamanders are aquatic and retain their 
gills throughout life. The European olm Proteus, under some con- 
ditions, does not lay its eggs but rather retains them in the oviduct 
where the young undergo development, finally to be born as sala- 
manders, which are but miniature replicas of the adult. In contrast 
