NO. 1552. NOTES ON MALA YAN PORCUPINES— LYON. 585 



in many respects like that of T/wcun/s, but rclativel}' narrower and 

 with less abrupt rostrum, and with a well marked fossa on side of 

 mandible beneath the condylo-coronoid notch and with rooted molars. 

 Differs from the skull of Trirhij>< in the absence of postorbital pro- 

 cesses, and in having distinctly heavier malars. 



Kiierwd characters. — Size small, a little less that of Thtcxrus, tail 

 long, about one third head and body. Entii'e upper parts and sides 

 of body and base of tail covered with heavy, somewhat flattened 

 spines, with a large groove on their dorsal aspect, and a shallow 

 groove on their underside at the base. The spines are longest on the 

 lower ))ack, rump, and base of tail where they are al)out 75 mm. long. 

 No quills proper are found on this porcupine, but interspersed among 

 the flattened, grooved spines on the lower l)ack are a few rounded 

 stiff bristles, somewhat quill-like at the base, having a length of 10(» 

 to 125 mm. The head, underparts, and the legs, are clothed with soft, 

 flat spines. The basal fourth of the tail is covered with spines, like 

 those of the lower back; the middle two-fourths are covered with 

 scales, each of which is subtendexi by three short hairs, a median stifl', 

 long one, with a shorter flner one on either side; the terminal fourth 

 of the tail is mainly covered with peculiar flattened hollow hairs and 

 some ordinary bristles. Each of these peculiar hairs begins with a 

 hair-like base, but soon expands into a small, narrow, hollow, flat- 

 tened capsule, followed by a short hair-like space and then another 

 flat, hollow capsule, some hairs having as many as Ave such expansions. 

 These hairs alwa3's terminate in an expansion with a long drawn-out 

 apex. (Plate LVII, fig. 3.) 



Skeleton. — The main features of the skull of the genus Athervrus 

 have previously been pointed out. The relative size and shape of the 

 skull and of its various parts are clearly shown in fig. 2, Plates LIV, 

 LV, and LVI, so that no detailed description is here necessary. The 

 vertebral formula is Cv. 7, D. li, L. 5, S. 3, Cd. 24. The axis bears 

 a large neural spine flattened from side to side, similar to that found in 

 Acanthloii^ but subtriangular in outline and directed backward at a 

 sharper angle. (Plate LVII, fig. 7.) The seventh cervical has a short 

 neural spine, like that of the sixth, and the long spine of the seventh 

 seen in AcantJdon. has been shifted backward to the first dorsal, as 

 in ThecKTvs. The lumljar vertebnv have rather narrow lateral pro- 

 cesses, directed forward at a more acute angle than they are in the two 

 preceding genera, and the ends of the processes are somewhat enlarged. 

 (Plate LVII, fig. 8.) Only three vertebra compose the sacrum in 

 Atheruras, and the first alone serves for the attachment of the ilia. 

 The presternum is relatively short, and its expanded portion rela- 

 tively narrow. The humerus is relatively more slender in Atherurns 

 than it is in Acanthlon or Thecurus,' the deltoid ridge is less promi- 



