94 Transactions of the 



seen in the Coprolites or fossil excrements of the reptiles, 

 and in the perfection of the remains. 



Grinoiclea. — Among the Stone Lilies or Crinoidea of the 

 Lias the most conspicuous is the Pentacrinite. These 

 Crinoideans are very remarkable fossils, consisting of innu- 

 merable tentacles spread in every direction, as if the animal 

 had been floating on the top of the water, when it had sud- 

 denly been surrounded and entombed. They belonged to the 

 class Eehinodermata, and so were allied to the starfish ; 

 they fastened on a stem which was attached to a rock and 

 there remained. Above this stem was a cup (containing 

 the animal's viscera), from the edges of which proceeded 

 innumerable arms branching out again and again into ten- 

 tacles, which served to seize food and convey it to the 

 mouth (situated at one side of the central cup). The animal, 

 in life, was covered with a soft integument, which has of 

 course decayed, and in the Encrinite the pulley screw has 

 been left exposed, the hollow interior being filled up vrith 

 lime. The starfishes found in the Lias occur principally in 

 the middle formation, and are mostly small, with long thin 

 arms. 



The Ammonites and Nautili next come under notice. The 

 Ammonites are principally divided into those with a dorsal 

 keel, and those without a dorsal keel. They are extremely 

 numerous in all the divisions of these strata, as well as in all 

 the formations of the Secondary Epoch ; but they are never 

 found in the Tertiary except in drifted fragments. The 

 Nautili are of the same order as the Ammonites, but are 

 much smaller in the body. Some representatives of them 

 are found in the seas of the present day. But of all the 

 relics of marine animals in the deposits of the Secondary 

 Epoch, none have excited so much curiosity and given rise to 

 so many conjectures as to their nature and origin, as the 

 fossils called Belemnites, vulgarly loiown as thunderbolts. 

 They are mostly of a long and fusiform shape, more or less 

 pointed at one end, and having, at the other, a conical cavity, 

 which is either occupied by a chambered shell (called the 

 phragmocone) or else filled up with the sand or stone in 

 which the Belemnite happens to be embedded. 



The substance of these bodies is always composed of calca- 

 reous spar, radiated in structure ; they are osselets of certain 

 eephalopods allied to the Sepia, and no doubt furnished, like 

 those animals, with ink-bag, mandibles, large eyes, and arms 

 bearing acetabula or suckers, although no traces of the soft 

 parts have hitherto been discovered. 



