The British Guiana Museum. 273 
After the very simple forms of the Animalcules which 
are at the bottom of the tree : so to speak, and of which no 
specimens are exhibited, the group of the sponges is placed; 
and following this group, though not proceeding direttly 
from it, comes the class of the Zoophytes (Hydrozoa) , while 
above this is placed the class of the corals and sea- 
anemones (Anthozoa). Above these spring the great 
groups of the Worms (Vermes) comprising some very 
simple forms and others very complex. From these, in 
one dire6tion, branches off the class of the star-fish and 
sea-urchins (Echinodermata) ; in another, the great group 
of the joint-footed animals (Arthropoda) , comprising the 
inserts, crustaceans, arachnids, and myriapods ; while in 
a third direftion, proceeds the great group of the shell- 
fishes (Mollusca) comprising the Polyzoa ) and the 
various classes of shell-bearing molluscs. All these 
forms, so far, belong to the great sub-kingdom of the In- 
vertebrate animals, that is, those destitute of a back-bone. 
To the worm-like stem belong various animals which 
present affinities to the lowest or most rudimentary of 
the Vertebrates, The great class of fishes (Pisces) forms 
the lowest division of Vertebrates, and close upon this 
comes the class of the frogs and toads (Amphibia). 
Next is placed the class of the reptiles (Reptilia) ) and 
then the birds (Aves) ; while above this comes the great 
class of the milk-secreting animals (Mammalia) , whose 
highest chara6leristics culminate in man, as the " flower 
of the ages." 
The animals of British Guiana correspond generally 
with those of other parts of South America and with those 
of tropical North America. So closely do the animals of 
these distri6ls resemble one another, that the whole area 
