rROCEEDINGti OF THE XATIONAL MUSEUM. 



and the Malay Peninsula,'^ on which the number of known forms is 

 only four or five. On the smaller islands of the archipelago, however, 

 both kanchils and napns, but especially the latter, show an excessive 

 tendency to differentiate into local forms, no less than 41 of which 

 are now known.^ A particularly striking example of this tendency 

 is furnished b}' the napus of the Rhio-Linga Archipelago. 



The Rhio-Linga Archipelago is a series of small islands extending 

 southeastward along the east coast of Sumatra from the southern 

 extremity of the Malay Peninsula (see map, fig. 1). The northern- 

 most of the islands, Karimon, Batam, and Bintang are separated 

 from the mainland by the narrow Malacca Strait on the west and 

 Singapore Strait on the east, the average width of which is only 

 about 10 miles. Singapore Strait contains a mass of small islands 

 on the north side, west of Singapore, which narrows the open Avater 

 at that point to 5 miles. The easternmost, Karimon, Kundur, and 

 Durei, are equally near the coast of Sumatra. From Karimon, the 

 northwesternmost of the group, to the south shore of Sinkep, the 

 southernmost, is a distance of about 150 miles, while that from Kari- 

 mon east to Panjang is about 125 miles. Near the middle the archi- 

 pelago is partly divided by the Rhio Strait into two main groups, 

 the Rhio '^ Archipelago proper at the north and the Linga Archi- 

 pelago at the south. The principal islands of the Rhio Archipelago, 

 the main axis of which extends east and west, are : Karimon, Kundur, 

 Durei, Durian, Sugi, Chombol, Bulang, Batam, Rempang, Galong, 

 Bintang, and Panjang. Of the Linga Archipelago, the main axis of 

 which is nearly north and south, the more important islands are 

 Sebang, Bakong, Linga, and Sinkep. In addition to these, the largest 

 of which, Bintang, Linga, and Sinkep, are from 25 to 35 miles across, 

 and roughly some 500 to 700 square miles in area, the archipelago con- 

 tains an almost infinite number of smaller islands and islets. The 

 entire group lies in shallow water, mostly within the 20- fathom line, 

 though Malacca and Singapore straits reach a depth of about 30 

 fathoms, while an isolated sounding of 49 fathoms is recorded be- 

 tween Singapore Island and Batam. The average depth of the water 

 between the archipelago and Sumatra is less than in the straits, that 

 separating the Linga group from the larger island nowhere exceed- 

 ing 20 fathoms, while that between the Rhio group and the coast 

 scarcely reaches 10 fathoms. The size of the archipelago as com- 

 pared Avith that of Sumatra and the Malay Peninsula is difficult to 



" Perhaps of Java and Borneo, also ; but the material from these islands is at 

 present unsatisfactory. 



*A11 but nine of the described forms of TraguJus have been discovered by 

 Doctor Abbott. 



f^ The spelling Rhio is found on most German, English, and American maps; 

 according to the Dutch authorities it should be Riouw. 



