Terrestrial Amphipoda — - Hurley 
115 
Carter (1931) considers that the majority of 
terrestrial animals have reached the land by 
way of fresh water rather than directly from 
the sea. 'The suggestion is made that this has 
been partly caused by the favourable series of 
intermediate environments between the fresh 
waters and the land, and that the evolution of 
many of the numerous adaptations necessary 
for terrestrial life has been induced in these 
environments serially and therefore with 
greater ease. The much greater variability of 
the fresh-water environments has undoubtedly 
been important in producing this result. The 
importance of the tide in maintaining the 
constancy of conditions on the marine littoral 
is emphasised.” 
Yet neither amphipods nor isopods fit 
this general pattern. Among the constituent 
groups of the cryptozoic fauna Dendy (1895) 
includes "isolated representatives of typically 
aquatic groups of animals which have as yet 
become little modified in accordance with 
their new life.” He comments, "Every natu- 
ralist knows how many small animals swarm 
beneath half-dry stones on the seashore. Such 
species appear to me to be taking the first 
step towards a terrestrial life. Gradually, they 
will make their way inland, still keeping be- 
neath logs and stones for the sake of moisture 
and coolness, until finally they accustom 
themselves to a thoroughly terrestrial exist- 
ence. In this section of the cryptozoic fauna 
we must place the shrimplike Amphipoda and 
Isopoda which certainly look strangely out of 
place on land.” 
Edney (1954) speaks similarly of the iso- 
pods. "There is little doubt that the route to 
land was across the littoral zone rather than 
by way of estuaries and swamps (Pearse, 
1929 ) . Evidence for this is the existence today 
of littoral and halophilic forms such as Ligia 
sp. and Halophiloscia, which are undoubtedly 
primitive morphologically.” 
These views are further supported by the 
fact that the genera Talorchestia, Talitrus, and 
Orchestia all embrace supralittoral as well as 
terrestrial species, whilst the fresh -water spe- 
cies of the family Talitridae all belong to 
genera which are represented only in fresh 
water and are morphologically closer to the 
marine genera of Talitridae than to the supra- 
littoral and terrestrial genera. The constancy 
of conditions on the marine littoral seems to 
have barred neither amphipods nor isopods 
from entering the terrestrial environment. 
The forest floor was perhaps the most suit- 
able place for a littoral animal to enter, espe- 
cially considering that "animals crossing [the 
littoral] zone may well be subjected to ex- 
tremely high temperatures” (Edney, 1954). 
In many lands, the forest reaches right to the 
water’s edge or borders streams running 
down to the sea, and often beaches are the 
only barriers between sea and forest. In these 
places, the supralittoral zone is the beachhead 
for invasion by littoral species. And, in coun- 
tries bordering the Pacific where the climate 
is relatively humid and the conditions of the 
forest floor are more or less uniform through- 
out the year, the leafmould zone is relatively 
moist and stable. Light intensity is considera- 
bly reduced by the nature of the zone itself, 
and by the strata of the forest canopy above. 
Humidity and temperature are relatively con- 
stant. "Forest temperatures are generally 
lower in summer and higher in winter than 
temperatures of adjacent areas. Similarly for- 
ests are cooler during the heat of the day and 
warmer during the night than areas external to 
them. Relative humidity is characteristically 
higher and evaporation rate lower within the 
forest than in adjacent, less dense terrestrial 
communities. Similarly, relative humidity is 
higher and evaporation rate lower within for- 
ests during the night than in daytime” (Allee, 
Emerson, Park, Park, Schmidt, 1949, refer- 
erences omitted). These tendencies towards a 
stable and more equable climate are intensi- 
fied in the leafmould zone which, of its na- 
ture, has an insulating effect from the sur- 
rounding atmosphere. "The cryptozoa are not 
only sheltered by the growth of the forest and 
shrub which mitigates the extremes of light 
and temperature, but they are further covered 
