The royal natural history . The group is divided into the two ordersPolyplacophora and Aplacophora; and is regarded by some authors, and perhapscorrectly, merely as an order of Gastropoda, and not forming a distinct class. Chitons,—Order Polyplacophora. The well-known chitons (Chiton idee) are the only forms included in thisorder, and are externally recognised by their shells consisting of eight separate pieces or valves, asthey are termed,which are arrangedover the back, andconnected at the sidesby the tough marginof the mantle inwhich they areembedded. In mostcases the valves areclose togeth
The royal natural history . The group is divided into the two ordersPolyplacophora and Aplacophora; and is regarded by some authors, and perhapscorrectly, merely as an order of Gastropoda, and not forming a distinct class. Chitons,—Order Polyplacophora. The well-known chitons (Chiton idee) are the only forms included in thisorder, and are externally recognised by their shells consisting of eight separate pieces or valves, asthey are termed,which are arrangedover the back, andconnected at the sidesby the tough marginof the mantle inwhich they areembedded. In mostcases the valves areclose together, extendright across the back,and are exposed ; butin some genera theyare far apart (Cryp-toplax), and in othersentirely covered by the mantle (Cryptochiton). The foot occupies the entireventral surface of the body, and the mantle covers the upper surface, extend-ing laterally beyond the shell. This portion is known as the girdle, and isnearly always covered with spines, scales, or spicules, which, to some extent, are. common chiton {Chiton, squamosus). CHITONS. 399
Size: 2294px × 1089px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, booksubjectnaturalhistory, booksubjectzoology
