24 



OUTLINES OF GEOLOGY. 



II. 



Class. 



Aves, 



Order. Family. Instances of Genera. 



The orders, families, and genera of birds 

 are of little importance in geology. 



Chelonia, 



Turtle. 



III. Reptilia. t 



Sauri, 



Ophidia, 

 Batrachia, 



IV* Pisces. 

 48. 



f Extinct, 



Crocodile, 

 ^ Lizard, 

 | Iguana, 

 L Chameleon, 



JAngues, 

 Serpentes, 

 ( Grana, Frog. 

 I Triton, Newt. 



{ Fish are arranged in two sections, the 

 ( bony and the cartilaginous. 

 Of Articulated animals there are four classes : — 



1. Crustacea, as the crab ; 



2. Arachnides, as the spider ; 



3. Insecta, 



4. Annulata, as the earthworm. 



49. Of Moluscous animals the softer parts generally dis- 

 appear when they become fossil. Their only important 

 character in geology, therefore, is derived from their shells. 

 These may be Univalve, Bivalve, or Multivalve, and the 

 two former may be either unilocular or multilocular, accord- 

 ing as the space within the shell is composed of a single 

 chamber, or of many, separated by partitions. 



50. Of radiated animals it is only necessary for our pur- 

 pose to be acquainted with the classes of Echinodermata and 

 Polypi. The former includes the Asterias or star-fish, the 

 Echini or sea-eggs, and the Encrinites. The latter comprises 

 Madrepores, Corals, and Sponges. 



Such is the progress that has been made in the study of 

 comparative anatomy, that it is now possible, from the exa- 

 mination of a single bone, to determine the species, genus, 

 and family of the animal to which it belonged. In the case 



