506 GEOGRAPHICAL ZOOLOGY. [PART iv. 



FAMILY 6. BELEMNITHLE. Fossil. (6 Genera, 100 



Species). 



DISTRIBUTION. Lias to Chalk in Europe, India, and North 

 America. 



Order II.TETRABRANCHIATA. 



FAMILY 7. NAUTILID^E. (1 Genus, 3 Species, Living; 4 

 Genera, 300 Species, Fossil). 



DISTRIBUTION. Indian and Pacific Oceans ; and the fossil 

 species from the Silurian Period to the Tertiary, in all parts 

 of the world. 



FAMILY 8. ORTHOCEKATID^E. Fossil. (8 Genera, 400 



Species). 



DISTRIBUTION. Lower Silurian to Lias. 



FAMILY 9. AMMONITIDJE. Fossil. (14 Genera, 1100 



Species). 



DISTRIBUTION. Upper Silurian to Chalk. Found at 16,000 

 feet elevation in the Himalayas. 



