578 
PROCEEDINGS of the national museum. 
VOL, JtXJUJ. 
Sufeikitrilsr HYSTlfclCIN'J9EB. 
The subfamily IlystrieiTue is characterized among the Hystricidne 
by having a short external tail, without a well-marked hairless scaly 
portion between its base and apex, in having the terminal hairs of the 
tail modified into hollow eapsule-like structures, mostly open at the 
ends, in the possession of well-developed quifis on the back, in having 
four sacral vertebrae, and rootless, hypsidont molars* It contains 
three genera: Hystrix (not considered in these notes, because not , 
found in the Malayan subregion), Acantliion , page 578, and Thecarm, 
page 582. 
AC A NTH ION F. Cuvier. 
1822. Acanlhiun F. Ccvieh, Mem. Mue, Hist, Nat. Parin, IX, 1S22, p. 418, p], xx 
bis, figs. 3, 4. 
Type . — Acanthion jtwanicum , from Java. 
Species. — A cant A ton brachyurum, (Linnieus), Malay Peninsula; A, 
longicmirtum (Marsden), Sumatra; A. jemmzeum F. Cuvier, Java; 
A. cramspinw (Gunther), Borneo. 
Diagnostic characters. -Externally similar to Hy&trix, but without 
a crest or mane and quills not so long. Cranially it differs in having 
much smaller nasals, extending back only as far as on a level with the 
lachrymal bones, and contained into the dorsal outline two and one- 
half times, instead of extending as far back as the squamosal roots of 
the zygomata and contained into the dorsal outline one and one-half 
times, as in Hystrix, No depression on upper surface of skull at the 
union of sagittal and coronal sutures. Molars rootless. 
External characters. — Size large; head and body about COD to 700 
mm.; tail short, about one-fifth length of head and body. Upper sur¬ 
face of head clothed with stiff, rounded, bristly hairs, those on the 
nape considerably elongated, but not forming the well-defined mane 
or crest found in llijdrir. Upper half of back and shoulders covered 
with flattened spines, usually each with dorsal and sometimes ventral 
grooves. About the middle of the back these spines replaced by large 
heavy quills, light in color, with a single dark band near the middle 
or toward the basal side of the middle. The quills vary in length 
from 50 to 250 mm., and are longest toward the middle of the buck, 
becoming quite short near the rump, where, however, they are still 
quills and bear no resemblance to the flattened spines found on the 
upper half of the back. On the base of the tail the quills become 
longer again. The distal portion of the tail is clothed with peculiar 
hairs. (Plate LV1I, fig. 1.) The basal portion of each (10 to 15 mm.) 
is quite hair-like, but it abruptly expands out into a hollow cylinder, 
like an elongated capsule, about 5 mm. wide and about four to five 
'times as long. Nearly always the ends of these capsule-like hairs are 
open, but rarely the sides of the capsule are prolonged to meet in a 
