578 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxii. 



SubfaiTiiljr HYSTKICIN-^zE. 



The subfamily Hystricinas is characterized among the Hystricidae 

 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 capsule-like structures, mostl}^ open at the 

 ends, in the possession of well-developed quills on the back, in having 

 four sacral vertebra?, and rootless, hypsidont molars. It contains 

 three genera: Hystrix (not considered in these notes, because not 

 found in the Mala^^an subregion), Acanthion^ page 578, and Thecurns^ 

 page 582. 



ACANTHION F. Cuvier. 



1822. Acanihion F. Cuvikr, Mem. Mus. Hist. Nat. Paris, IX, 1822, p. 413, pi. xx 

 bis, figs. 3, 4. 



Type. — Acanthion javanicum, from Java. 



Species. — Acanthion hrachyuru),), (Linnaeus), Malay Peninsula; A. 

 longicauduvi (Marsden), Sumatra; A. javaniciim F. Cuvier, Java; 

 A. crassispinis (Giinther), Borneo. 



Diagnostic characters. — Externally similar to IIystrh\ but without 

 a crest or mane and quills not so long. Cranially it differs in having 

 much smaller nasals, extending back onl}^ 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 Ilystrix. No depression on upper surface of skull at the 

 union of sagittal and coronal sutures. Molars rootless. 



External cliaracters. — Size large; head and body about 600 to 700 

 mm. ; tail short, about one-tif th length of head and bod3^ 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 Ilystrix. Upper half of back and shoulders covered 

 with flattened spines, usually each with dorsal and sometimes ventral 

 grooves. Al)out 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 back, 

 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 LVII, 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 



