60 LABORATORY DIRECTIONS IN 



5. Last cervical and first body vertebrae articulated by centrum and 

 zygapophyses, or (6) articulated by zygapophyses only. 



7. Marginal bones forming a complete series, or (8) absent or in an 

 incomplete series. 



9. Squamosal and parietal bones separated, or (10) forming a suture. 



11. Limbs not paddle-shaped, or (12) paddle-shaped. 



13. Nuchal plate with costiform processes, or (14) without costiform 

 processes. 



15. Plastron composed of nine bones, or (16) eight bones, or (16a) 

 eleven bones. 



17. Caudal vertebrae mostly opisthoccelous, or (18) proccelous. 



Some of the families are given below with the characters, and these 

 families are represented by specimens. Study the specimens with the list 

 of characters, determine the families to which they belong and describe 

 each family in your notes. 



Family Cheloniidse. Characters 1, 3, 5, 7, 10, 12, 14, 15, 18. 

 Family Trionychidse. Characters 1, 3, 6, 8, 9, 11, 13, 15, 18. 

 Family Chelydridaj Characters 1, 3, 5, 7, 9, 11, 13, 15, 17. 

 Family Pelomedusidse. Characters 2, 4, 5, 7, 9, 11, 14, 16a, 18. 

 Family Kinosternidae. Characters 1, 3, 5, 7, 9, 11, 13, 16, 18. 

 Family Testudinidae. Characters 1, 3, 5, 7, 9, 11, 14, 15, 18. 



E. SUBDIVISION OF THE FAMILIES 



To THE TEACHER. It is expected that the teacher will at this point 

 introduce keys to the genera and species of some one or a few groups of 

 animals. The group selected should preferably be represented in the 

 general region where the work is being done so that the exercise will both 

 acquaint the student with species with which he will come in contact and 

 with the characters used to differentiate the subdivisions of the family. 

 The teacher should select groups with which he is most familiar and of 

 which representative specimens can be most easily acquired. The keys 

 may be compiled from general systematic treatises or from state mono- 

 graphs. As examples of the works which may be used the following may 

 be cited: 



GENERAL SYSTEMATIC TREATISES: 



CHAPMAN, Handbook of Birds of Eastern North America. 

 BAILEY, Handbook of Birds of Western United States. 

 DICKERSON, The Frog Book. 



JORDAN, A Manual of the Vertebrate Animals of the United States. 

 WALKER, A Synopsis of the Classification of the Fresh-water 

 Mollusca of North America, North of Mexico. 



