BROOK AND ATHERFIELD 33 



Cuttle-fish, is the highest division of the Mollusca. The 

 animals all possess heads with eyes, and tentacles around 

 the mouth. They nearly all possess a shell, either external, 

 as in the Nautilus, or internal, as in the cuttle-fishes, the 

 internal shell of which is often washed ashore after a 

 rough sea. The Cephalopods are divided into two orders. 

 The first includes the Cuttle-fish and the Argonaut or 

 Paper Nautilus. Their tentacles are armed with suckers, 

 and they have highly-developed eyes. They secrete an 

 inky fluid, which forms sepia. The internal shell of 

 extinct species of cuttle-fish, of a cylindrical shape, with 

 a pointed end, is a common fossil in various strata, and 

 is known as a Belemnite (Gr. /SfAs^vov, " a dart".) 

 The second order includes the Pearly Nautilus of the present 

 day, and the numerous extinct Nautiloids and Ammonoids. 

 The tentacles of the Pearly Nautilus have no suckers ; 

 and the eyes are of a curiously primitive structure, what 

 may be called a pin-hole camera, with no lens. The 

 shells of the Nautilus and its allies are of simpler form, 

 while the Ammonites are characterised by the complicated 

 margins of the partition walls or septa, by which the 

 shells are sub-divided. The chambers of the fossil 

 Ammonites have often been filled with crystals of rich 

 colours ; and a polished section showing the chambers 

 is then a most beautiful object.* 



Continuing along the shore, we come to the Lower 

 Exogyra group, where Terebratula setta is found in great 

 abundance. A reef with Exogyra sinuata runs out about 

 350 yards west of Whale Chine. The group is 33 ft. thick, 

 and is followed by the Scaphites group, 50 ft. The beds 

 contain Exogyra sinnata, and a reef with clusters of 

 Serpulae runs out from the cliff. In the middle of the 

 group are bands of nodules containing Macroscaphites 

 gigas. The Lower Crioceras bed (16 ft.) follows, and 



' Some fine ammonites may be seen at the Clarendon Hotel, 

 Chale, one about 5 ft. in circumference. 



