90 USEFUL PLANTS OF GUAM. 
Among the mollusks are a number of handsome olives, cones, and 
many small cowries which evidently feed upon the coral. There are 
also naked mollusks that protect themselves by spurting forth clouds 
of purple fluid. File-fishes, tetrodons, and other fishes are always 
seen nibbling at the coral. Sometimes a great sea porcupine makes 
for them, and off they all swim as though afraid for their lives. 
The natives eat many kinds of marine animals, but they do not 
depend upon the reef to the extent that the Samoans and Caroline 
Islanders do, having become essentially an agricultural people, and 
few of them find it to their advantage to neglect their fields for fish- 
ing. In former times several governors found it profitable to collect 
and dry certain kinds of holothurians, called **trepang.” or ‘* béches 
de mer,” and ship them to Manila or Canton:” but these animals are 
no longer sought in Guam, and are seldom eaten by the natives. 
Crabs of several kinds abound, most of them of wide distribution in 
the Pacific. Some of them (**alimasag”) have shells brightly decorated 
with orange-red spots (Zos7ius aeneus (1.)), others are covered with 
spines, and others, when they fold in their claws, look like smooth, 
waterworn bowlders. Serambling over rocks alone the shore are 
Grapsus grapsus tenuicrustatus (Herbst.), of a deep red color, speckled 
and striped with yellow. Spiny lobsters or crayfish (Panulirus), with 
long antenne and carapax covered with spines, abound at certain 
points along the coast; and in the fresh-water streams on the islands 
are delicate semitransparent prawns (Bithynis), which move about the 
pools ina stealthy ghostlike manner, and are almost invisible to the 
casual observer, Both the spiny lobsters and the prawns are valued 
as food. 
Among the land crabs is Card/soma rotundum Q. & G., which bur- 
rows In the ground and does great damage to gardens. ‘This is caught 
in traps made of bamboo by the natives. It visits the sea at regular 
intervals to deposit its eges, going after nightfall in straight lines 
and climbing over all obstacles in its way. Among the hermit crabs 
are Anieulus aniculus (Herbst.), with a ved carapax ornamented with 
deep red spots, and Durdanus punctulatus (Olivier), prettily marked 
with blue ocelli with white centers. The most interesting of all the 
land crustaceans is the well-known Bérgus latro (L.), or robber crab, 
called “ayuyu,” which is kept in captivity by the natives and fattened 
on coconuts for the table. 
INSECTS. ” 
The insects of Guam have never beensystematically collected. Many 
of those now occurring on the island have undoubtedly been introduced 
“Chamisso, Tagebuch, p. 243, 
’T am indebted to Dr. W. TH. Ashmead, of the U.S. National Museum, for the 
names of the insects mentioned. 
