38 SNAKES OF THE PHILIPPINE ISLANDS 



173. Tidog (see ahas-na-tulog) . 



174. Uao-uao (Misamis), Latwauda coluhrina. 



175. Ugalupong (Bohol). 



176. Ugu (Cagayan and Isabela). 



177. TJringan (Cagayan and Isabela) . 



178. Viracac (Ilooos Sur). 



179. Walo-iualo (Negros), Lapemis hardwickii. 



FAUNAL RELATIONS AND DISTRIBUTION OF PHILIPPINE SNAKES 



The herpetological faunas of the Philippines, particularly the 

 ophidian fauna, are derived from a variety of sources, but un- 

 doubtedly their greatest affinity is with Borneo. A casual 

 glance at a map shows the Philippines joined to surrounding 

 land bodies by a series of island chains, five or six in number. 



To the north there is but a single chain comprised of the 

 Babuyan and Batan Islands. This chain reaches nearly to For- 

 mosa, which in turn is joined with Japan through the Riu Kiu 

 Island group. To the south and southwest there are no less 

 than three island chains that connect with Borneo. The most 

 important of these three is the Palawan Island group, including 

 the Calamianes, the Cuyo Islands, Palawan, and Balabac. The 

 second chain, not so clearly defined as the former, comprises the 

 Cagayan Islands, and Cagayan Sulu. The third chain which 

 approaches more nearly to the mainland is the Sulu Archipelago, 

 which includes a number of island groups, and the larger islands 

 Basilan, Jolo, and Tawitawi, with numerous small islands. As 

 might be suspected the Philippines have far more genera and 

 species in common with Borneo than mth any other land body. 

 To the south there is a second chain which divides, one branch 

 connecting with Celebes through the Sanghir Islands, and the 

 other with Gilolo, and the Moluccas, through Talaur, and Morotei. 



There are thirty-three recognized genera of land snakes known 

 to occur in the Philippines, and five of these are endemic. They 

 are Oxyrhahdiiim, Cjidocorus, Haplonodon, Tiiphlogcophis, and 

 Hologerrlmm. The first genus has two known species; each of 

 the other four is represented by a single species. 



Two other genera found in the Philippines have not been 

 found in Borneo. These are Hemibitngai-iis and Stcgo)wtus. 

 The first of these, of which there are three kno^ra Philippine 

 species, may have entered from the north, as the genus is repre- 

 sented on the mainland of Asia in India and two other species 

 are found in the Riu Kiu Islands. Stejneger states that no 

 species of the genus has been found in Formosa as yet, but 

 suggests the possibility of a discovery, mentioning that little 



