INTRODUCTION TO THE MOLLUSCA. vu 



species of Stomatetta, nine of Stomatia, sixteen of Genu, and a small new genus belonging 

 to the same group, were also procured by Mr. Cuming from the same locality, appearing 

 to represent the Haliotis family of Australia and the Chitonidce of America. The members of 

 this group are tolerably brisk in their movements, crawling among the stones and coral at high 

 water, and hiding under stones dining the reflux of the tide ; they have the power of sponta- 

 neously throwing off the hind part of the foot when taken, in the same manner as the Op/durus 

 parts with a ray, or a Crustacean a claw. Out of forty-seven species of Mangelia described 

 by Mr. Lovell Reeve in his beautiful monograph of that genus, no less than forty-three are from 

 these islands • then favourite^ locality is coarse loose sand, either sand-patches on the reefs, 

 or under stones in deeper water outside the reefs, or in still deeper water where the sand 

 is mixed with mud. The species which live at considerable depths, as M. abyssicola, cinna- 

 momea, and tenebrosa, are dark-coloured and strongly ribbed ; those that prefer the loose 

 sands are generally granulated, finely ribbed or cancellated, and of a light brown colour ; 

 while light-coloured species, as M. Marginelloides, which are seen crawling over mud-flats, 

 are often covered with a fuscous epidermis. Perhaps the amount of colour in shells depends 

 upon the degree of light they are subject to : as light does not penetrate lower than 700 

 feet, Mollusca dredged from very deep water are usually colourless, while species living 

 on the rocks are usually brightly coloured. On turning large stones, groups of Bicinula 

 Columbelloides, Bissoce, and other gregarious genera, as Truncatellce and Melampi, which 

 are amphibious, were constantly met with, and during the night Neritce were observed 

 crawling actively in company over the stones ; and in the pools within the barrier reefs, 

 numbers of Limes were observed darting rapidly about. In the Samboanga Roads very 

 few shells were obtained, as the tide sets through them with great rapidity, and no soundings 

 can be obtained further off shore than half a mile, where the floor is composed of dead coral, 

 black sandy mud, and loose pebbles; a coral reef, however, borders the shore all along 

 this part of Mindanao, within which the water is comparatively shallow and filled with 

 marine vegetation supporting numerous Fissurella and Emargimdee. In fresh-water ponds 

 and rivulets near the village of Calderas, Navicellce, Melanice, and Neritince were very 

 numerous ; but no Ancyli, Ampullar i<B, or Bivalves coidd be detected. The Bulimics chloris 

 was very abundant on the mountains : it glues itself to the under surface of leaves ; the eggs 

 are very large, oval, calcareous, and of the same size at each end, and the young shell, which 



