LAND REGIONS. 193 



Sap. In the Unionida?, some of the generic forms are closel}' 

 allied to So. American genera, as Pseudodon to Monocondjdfea, 

 Solenaia to Mycetopns, Arconaia to Hyria. The Andaman and 

 Nieobar Islands each possess many peculiar species. 



14. Indo-Malaysian Region. 



The islands of Sumatra, Java, Borneo, the Celebes, etc., form a 

 natural insular region ; to which the fauna of the peninsula of 

 Malacca is quite as closely related as it is to that of the Indo- 

 Chinese region to which it is attached. The section Amphi- 

 dromus, of Bulimus, is the most characteristic form ; but Nanina 

 is largely distributed, and represented by its most beautiful 

 species ; Clausilia is found in Sumatra, Java and Borneo ; the 

 genera of operculated land shells are numerous ; Melania pre- 

 dominates among the fluviatile mollusks. 



The mollusks of this region are most nearly related to those 

 of Indo-China. 



But little is known of the mollusks of Sumatra ; most of the 

 described species being common to Borneo and Java. In Java 

 191 species have been collected, 14 of which are operculated, 82 

 fresh-water, 17 common to Sumatra. 



Borneo, which is far from being completely explored, yields 

 16T species, of which 45 are operculated, 45 fresh-water. Of 

 these 167 species, 19 live also in Java, 13 in Sumatra, 16 in the 

 Indo-Chinese province, 18 in the Philippines; 100 species are 

 peculiar to the island. The brackish-water mollusks are remark- 

 able : Pholas rivicola burrows in floating logs used as landing- 

 places, twelve miles from the sea, up the Pantai River. The 

 mangrove swamps abound with Cerithidea,Terebralia, Potamides 

 and Quoyia ; Auricula and Scarabus inhabit damp woods. 



15. Philippine Region. 



The extraordinary richness of these islands has been developed 

 mainly by the researches of Cuming and Semper. The climate 

 is equable, with a temperature like that of South China 

 (66°-84°), woods are prevalent and the rains heavy — all circum- 

 stances favorable to the abundance of land shells. This region 

 has been called the paradise of mollusks, and in fact, nowhere 

 else upon the surface of the globe is there such a rich collection 

 of gorgeously colored shells — classed as Helix or Bulimus 

 according to the degree of elongation of the spire. It is supposed 

 that, as in the West Indian Islands, the fauna of each island is 

 largely peculiar to itself, but we do not possess the means of 

 verifying this supposition. The list prepared b}^ Kobelt com- 

 prises 586 species, 65 of which are opercvilate. There are 108 

 fluviatile gastropod mollusks. The Helices alone include about 

 half the total number of species, and of these the characteristic 



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