738 Marvels of the Universe 
FISHES OF THE OLD RED SANDSTONE. 
At an exceedingly remote period—and no one can say within a few million years how remote it was—these fish-like 
creatures existed, possessed of neither limbs nor lower jaws. Amongst these was the subject of the above photograph— 
Coccasteus. 
While it is impossible to deny that scale insects are capable of incalculable damage, it is interest- 
ing to note that certain species secrete substances valuable to mankind. The ‘‘ manna,’”’ endowed 
by the wandering Israelites with a miraculous origin, was almost certainly a kind of honey-dew 
produced by the Manna-bearer, a Coccid found on tamarisks in the Mediterranean district. This 
substance is still used as food by the Arabs, who call it “‘ man.’”’ The white wax of China is derived 
from Evicerus pe-la—another scale insect, found upon an indigenous ash tree. It was formerly 
greatly prized, but is now falling into disuse owing to the introduction of kerosene. In India, a 
similar wax is secreted by a scale insect known as the Wax-bearer. The wax secreted by other 
species of the latter genus has also been utilized by mankind. 
Again, a fatty substance containing a peculiar acid is produced by a Mexican Coccid. It is 
used as a varnish, which dries and hardens on exposure to the air; also as an external medical 
application in various ailments. The curios known popularly as ‘“‘ ground pearls”’ are the outer 
shells of the Pearly Coccids. In South Africa, and the island of St. Vincent, they are collected, 
strung together as necklaces, and sold to tourists. 
The most important products of scale insects, however, are lac and the crimson dye known as 
cochineal. Lac is secreted in large quantities by the Lac Coccid upon the twigs of its food-plants, 
fig, buckthorn, and other trees. It is imported to this country from India in its natural state, 
and after treatment forms the basis of varnish, French polish, and many other important 
materials. 
-FISHES OF THE OLD RED SANDSTONE 
BY R. I. POCOCK, F.R.S. 
ALTHOUGH the term “ fishes ”’ is ordinarily used in a vague and elastic sense for most animals that 
live in the sea, its scientific equivalent, “ Pisces,” is much more restricted in its application. In 
the zoological class “ Pisces,’’ for example, the lamprey and its allies find no place, being rigorously 
excluded therefrom because they differ from all species above them in the scale of creation, like sharks, 
