The British Guiana Museum. 243 
centipedes, form the great group of the joint-footed 
invertebrates (Arthvopoda). They agree in having the 
body ringed or segmented, and in having the limbs made 
up of many joints. They thus differ from the great group 
of the worms (Vermes) in which the body is ringed, but 
the appendages are unjointed. 
On the next table are shewn specimens of various 
kinds, chiefly of colonial and foreign minerals and ores, 
and of foreign fossils. Among them will be found two 
nuggets of gold from the Puruni river, with other 
specimens of gold-quartz from other parts of the colony ; 
a fine and very rich piece of auriferous quartz, from 
the Saramacca river, Surinam ; a specimen of silver ore 
from Bolivia ; specimens of quartz, mica, asbestos and 
blacklead ; ores of iron, copper, lead and tin ; a portion 
of the root of a fossil coal-plant ; a piece of Chinese 
soapstone, beautifully carved ; portions of granite and 
slate shewing dendritic and other markings {not fossil 
plants) produced by crystallisation ; various fossil shells, 
such as ammonites — belonging to the cuttle-fish class — 
sections of fossil wood, and a fine piece of letter-wood. 
On the side hangs the skull of a small whale, taken 
from a specimen that was stranded on the Essequebo coast 
some years ago. By many people, the whales, dolphins and 
porpoises are looked upon as fishes, like sharks — simply 
from the fa£l that these forms are aquatic and have a 
fish-like body. They are, however, quite distinct from 
fishes. They breathe air by lungs, not gills ; they suckle 
their young and are therefore true mammals which have 
lost their hind limbs from an aquatic mode of life, while 
the tail has taken the form of a broad horizontal fin — 
unlike the vertical caudal fin of fislies. They are 
