638 



ARTHEOPODA 



SUB-KINGDOM VII 



TABLE SHOWING VERTICAL RANGE OF TRILOBITES. 



Families. 



Order 1, Hypoparia 



Family 1. Agnostidae 



2. Harpedidae . 



3. Trinucleidae . 



Order 2. Opisthoparia 



Family 1. Conocoryphidae 



2. Olenidae 



3. Asaphidae 



4. Proetidae 



5. Bronteidae . 



6. Lichadidae . 



7. Acidaspidae . 



Order 3. Proparia 



Family 1. Encrinuridae . 



2. Calymmenidae 



3. Cheiruridae . 



4. Phacopidae . 



Total Number of Families 



18 



n 



[The foregoing chapter on the Trilobita has been abbreviated from an essay prepared 

 expressly for this work by our foremost authority on the group, Professor Charles E. Beecher 

 of Yale University, New Haven. About a score of new figures have also been introduced in 

 the text, borrowed mainly from Dr. Beecher's original contributions. These last should be 

 consulted by every student in connection with the present chapter. TRANS.] 



