vi INTRODUCTION TO THE MOLLUSCA. 



light-shelled Mactra perforate obliquely the yielding soil. On the reef Coiories and Stoma- 

 tellcB abound ; outside the barrier Marginella, Fusus, Pleurotoma, Clavatula, and Strombus ; 

 while in the deep water, more seaward, Terebratula, Cylichna, Nucula, and Necera are 

 met with. At Leegeetan, in Borneo, there are many miles of low rnangrove-swamp, partly 

 watered by trickling rivulets, where thousands of Tekscqpium and Potomis, or Cerithium 

 palustre, are seen partially buried in the mud, then' spires bristling the surface ; amongst the 

 tangled mangrove-roots were numerous Cassidulcs and Quoyice ; in the half-stagnant ponds " 

 MelanicR were abundant, and, crawling on the soft muddy banks, forming slender tracks, 

 were Nematwra and Assiminea ; in the damp woods near, Auricula Midce, Scarabi, and 

 Pedipes were obtained; Pterocyclos parvus, spiraculum, and spiracellum, and Cyclostoma 

 planorbulum were found among decayed leaves, in the fissures of rocks near the margin of 

 the forest, while Choanopoma concinnum and nitidum were seen inhabiting the foliage of the 

 trees ; Scarabi were very numerous, usually hiding under dead ieaves, but crawling about 

 briskly after rain. The number of herbivorous mollusca peculiar to Borneo, judging from 

 our limited exploration, does not seem so great as we might be led to expect from its 

 abundant vegetation and warm, humid atmosphere ; the large Helix Brookei and the 

 Bulimus Adamsii, together with Nanina vittata and some others, were, however, obtained 

 from this island. 



From the circumstance of the islands of the Eastern Archipelago lying within the 

 tropics, the equinoctial line extending nearly through the centre, the Mollusca partake of 

 characters exhibiting general uniformity ; but when one group is separated from the rest, 

 as the Philippine by the seas of Sooloo and Celebes, several peculiarities occur in their 

 distribution. The genera Stomatia, Gena, Stomatella, Mitra, Mangelia, and Liotia 

 appear principally confined to this group. Whether it is owing to the laborious and 

 successful efforts of the Prince of Collectors, Hugh Cuming, Esq., which have made the 

 Mollusca of these islands known, or whether to natural causes, it is certain these islands 

 harbour a vast number of forms. The constant flow of water towards these equinoctial 

 regions may tend to favour the submarine migration of Mollusca thither, added to which, 

 the vast stores of nutriment and the higher degree of temperature of the water, favour their 

 growth and reproduction. Upwards of fourteen species of Cyclostrema, as many of Liotia, 

 whose habitats are known, have been collected among the Philippine Islands ; whde sixteen 



