180 SUPPLEMENTAEY NOTES. 



14. FucoTDES. — Frond not symmetrical, often disposed on a flat surface; ribs none, or 



badly defined. 



15. Phyllites. — Leaves with ribs well defined, repeatedly divided, or anastomosing.' 



16. PoAciTES. — Leaves linear ; ribs pai-allel. 



17. Palmacites. — Leaves fan-sliape. 



Class IV. Organs of fructification. 



Order I. Carpolithes. — Fruits or seeds. 



Order II. Antholithes. — Flowers.^ 



The numerous additions and modifications, which subsequent experience and discoveries 

 have led M. Brongniart to introduce into his classification, will be found in an article recently 

 published (1849) in the " Dictionnaire Universel d'Histoire Naturelle," under the title of 

 " Tableau des Genres de Vegetaux Fossiles, consideres sous le point de vue de leur classification 

 botanique et de leur distribution geologique." 



V. Fossil Cephalopoda, Nautilus, Ammonite, &c. — The fossil remains of the molluscous 

 animals, named Cephalopoda, from their organs of prehension being arranged around the head or 

 upper part of the body, are the most ancient, numerous, and interesting, of this class of animated 

 nature in the mineral kingdom. These relics are among the most varied and striking of the extinct 

 beings that occur in the sedimentary strata, from the most ancient secondary formations, to the 

 most recent tertiary. The living species are but a feeble representation of the countless myriads 

 which must have swarmed in the ancient seas. 



The animal of the Cephalopods is composed of a body, which is either enclosed in a shell, as 

 in the Nautilus, or contains a calcareous osselet or support, as in the Sepia or Cuttle-fish ; it has 

 a distinct head, and eyes as perfect as in the vertebrated animals, with complicated organs of 

 hearing, and a powerful masticating apparatus, surrounded by arms or tentacula. Below the 

 head there is a tube which acts as a locomotive instrument, to propel the animal backwards, by 

 the forcible ejection of the water that has served the purpose of respiration, and which can be 

 ejected with considerable force by the contraction of the body. 



Their fossil remains consist of the external shell and the internal osselet ; and in the naked 

 tribes, of the soft parts of the body, the ink-bag, &c., as noticed in the account of the Belemnite 

 and Belemnoteuthis. 



The shell varies exceedingly in the different genera. In the group characterised by smooth 

 septa, and a medial or submedial siphuncle, as the Nautilus, the earliest or most ancient type is 

 straight, as in the Orthoceras (Plate LVIII. fig. 14) of the palaeozoic formations ; the intermediate 

 forms present various modifications of the spiral, and terminate in the completely discoidal shell of 

 the living genus ; while the other group, that with sinuous or foliated septa and a dorsal siphuncle, 

 commences in a discoidal type — the Ammonite, which gradually passes through the various 

 modifications of Crioceras, Scaphites (Plate LXI. fig. 10), Hamites (Plate LXI. fig. 3), Turrilites 

 (Plate LXI. fig. 12), &c. ; and finally becomes extinct in the straight Baculites (Plate LX. fig. 2). 



In argillaceous strata, as the Kimmeridge and Oxford clay, London clay, &c., the shells of 

 Cephalopoda are oftentimes beautifully preserved ; the chambers are frequently filled with the 

 solid matrix, but in many instances these cavities are lined either with brilliant pyrites or spar. 

 Stony or sparry casts of the cells or chambers, the shell having perished, are another common 



' The character of the ribs here given belongs exclusively to leaves of plants of the dicotyledonous tribe ; as those of the 

 next genus Poacites equally restricts them to the other great tribe of monocotyledonous plants. 

 ^ These orders are too little known to be divided at present into genera. 



