x INTRODUCTION TO THE MOLLUSCA. 



Among these islands we were fortunate enough to discover four new species of Chitons, 

 a circumstance the more satisfactory from the fact of so few species of this genus having 

 been noticed in the Asiatic region, and most of those confined to the Philippine Archipelago ; 

 for while the Australian region boasts of the greatest number of Haliotides, the American can 

 muster the largest amount of Chitons, and the other zoological regions would appear to be 

 remarkably deficient in both genera. Out of one hundred and forty-three species described 

 and figured in Mr. Reeve's beautiful monograph of the genus, sixty-six come from America, 

 forty-two from Australia, fourteen from Asia, twelve from Europe, and nine from Africa. 

 But two or three have been found in the Pacific, while ten are peculiar to the Philippines. 

 Chiton hirudiniformis was found by us among these islands, and is also peculiar to the 

 Gallapagos Archipelago ; and C. spiniger, of the Philippines, appears to represent C. occiden- 

 talis of the West Indies. The largest and most brilliant species come from the tropical 

 seas ; the smallest and most obscure from cold climates, or from considerable depths, in 

 accordance with the known laws of geographical distribution. Northern Chitons have the 

 valves covered either partially or entirely by the mantle, as in Chiton Sitkensis, C. tunicatus, 

 and C. auriculatus ; the C. chlamys will probably be found to have come originally from a cold 

 climate. I have frequently found Chitons among the islands of the Oriental Archipelago, 

 adhering to the stones in the society of Neritce and Patettte, at very considerable distances 

 from the water, and perfectly exposed to the burning rays of a tropical sun. At Cape Rivers 

 we discovered, adhering to stones on the reefs, three new and beautiful species, namely, 

 Chiton petasus, C. acutirostratus, and C.formosus. 



The floor along the eastern coast of Africa consists of fine clear sand, forming in many 

 situations vast accumulations, like the Agulhas bank projecting from the Cape, which arises 

 to within a few fathoms of the surface. These banks are prolific in Ancillarice, Margimllee, 

 and BullicB. The shells collected at the St. Brandon Shoals, or Gargados Garajos, were 

 remarkable for their white appearance ; Valuta costata, Cerithium, and Cardium were all of 

 this colour, as were also the only species of Cone {Conns verrucosus) and of Pleurotoma 

 P. virgo). — A. A. 



