FISHERIES AND GUANO INDUSTRY OF PERU. 349 
word means saltpeter, but it is applied by them to what is merely a natural 
mixture of salt and sand and other impurities, which may be found near some 
of the villages. It is claimed by many of the Indian fishermen that the fish 
preserved with the so-called salitre will keep in better condition for eating than 
those preserved with pure salt. 
The crude native methods of drying anchobetas have already been noted. 
Occasionally these little fishes are prepared in small quantities, by pickling, so 
as to make a very palatable food. 
Generally speaking, no choice is exercised in the selection of fish for pres- 
ervation; any fish that comes to hand and is regarded as edible will be packed 
away. There are certain forms of preservation, however, which seem to be 
worthy of further description. 
Preservation methods at Mollendo.—The fisheries of Mollendo, though not 
extensive, would form a chapter in themselves. The markets of the port and 
of Arequipa, the second city of the country, display a variety of fish ee 
not seen in the more northern markets. 
On some accounts the most interesting fishery product of this region is the 
peculiar dry and tangled egg-mass which is found on the local markets as 
““cau-cau.’’ This is the egg-mass of the ‘‘ volador”’ or flying fish, which is collected 
in season and dried that it may be kept on the markets throughout the year. 
These eggs have an especial interest from the fact that, although flying-fish eggs 
have been known to science for nearly fifty years, they were, until quite recently, 
attributed erroneously to the little sargasso fish (Pterophryne) of supposed nest- 
building habits. A few years ago, after the discovery of the true eggs of Ptero- 
phryne, the identity of the eggs of the so-called ‘“‘nests’’ with those of the flying 
fishes was soon established. The cau-cau appears to have been a product long 
familiar to the natives of this part of Peru, by whom the eggs have been attrib- 
uted, and correctly as it seems, to the flying fishes. 
Each egg is 2 millimeters in diameter, and its membrane is produced into a 
number of filaments, which, though rather scattered over the surface of the egg, 
have a tendency to a bipolar distribution. The filaments, though very fine, are 
quite long and the fibers of different eggs are thoroughly intertangled, to unite 
the many eggs into a closely woven mat. Sometimes the filaments are so twisted 
together as to give the appearance of a well-defined thread. 
The cau-cau of the market, then, is a large number of the shrunken berries, 
entangled to form a shapeless mat. A mat may be a good double handful or 
more, and the filaments are so completely interwoven as to make it difficult to 
tear the mass into portions. When soaked in water the eggs will expand and 
take an appearance as if freshly laid. They are found in early summer, begin- 
ning with October, and are said often to be entangled with weed. My visit 
was in July (midwinter) and the cau-cau then on the market was quite free from 
