576 PROCEEDINGS OF THE NATIONAL- MUSEUM. vol. xxxii. 



considered synonymous with part of Ilystrix. However, the material 

 at hand shows very considerable differences between Ilystrix proper 

 and Aaintldon^ which will be pointed out further on. With regard 

 to some of the species in the various genera of Malayan porcupines, I 

 have not seen a sufficient number of specimens to determine the char- 

 acters satisfactorily. Where several forms of one group, each form 

 occupying a definite and isolated geographic area, have been named I 

 have made use of the names bestowed upon them even if their specific 

 characters are not clear, believing this plan better than to place them 

 under one specific name, for material is as lacking to show their iden- 

 tity as it is to show their distinctness. 



The list of works to which reference has been made in preparing 

 these notes will be found under the synonymy of the different species 

 or referred to in footnotes. The specimens on which these notes are 

 based are listed in the table of measurements, page 593. They repre- 

 sent forty individuals from Malaya, thirty-three skins with skulls, two 

 odd skulls, and five skeletons. All but three of these specimens were 

 collected by Dr. W. L. Abbott, and have been presented by him to 

 the U. S. National Museum. 



KEY TO THE GENEBA OF MALAYAN PORCUPINES. 



a Tail short, less than one-fourth length of head and body; caudal hairs terminating 

 mostly in hollow capsule-like structures, molars rootless, sacral vertebrae 



four Su})family HvsTRiciNyE, p. 578 



6 Dorsal profile of skull arched, nasals extending back to level of lachrymals, and 



contained into dorsal outline two and one-half times Acanthkm, p. 578 



hh Dorsal profile of skull nearly straight, nasals extending back to level of anterior 

 border of infraorbital foramen, contained into dorsal outline three and one- 

 half times Thecurus, p. 582 



aa Tail long, one-third t© one-half length of head and body, terminating in a tuft of 

 modified bristles, molars rooted, sacral vertebrse three. 



Subfamily Atherurin^e, p. 584 

 c Each caudal scale subtended by three hairs, terminal bristles alternately 



expanded and contracted Atherurits, p. 584 



cc Each caudal scale subtended by a single hair*, terminal bristles of uniform 

 width throughout Tridnjs, p. 588 



Tabular view of the principal external and cranial character's of the genera of Old World 



porcupines. 



Tail short, less than one-fourth head and body 



Tail longer, one-third to one-half head and body . 

 Tail longer, one-half head and body 



Caudal hairs termhiating mostly in a hollow, open, capsule-like structure four 

 to five tinu's longer than wide'. 



Caudal hairs terminating mostly in a hollow, open or closed capsule-like struc- 

 ture tliree times longer than wide 



Caudal liairs, flattened bristles alternately expanded and contracted 



Caudal hairs, flattened bristles of uniform width throughout 



