131 



C Ventral plates 210 to 240. No. 19. King Snake. Page 174. 



CC. Ventral plates 180 to 210. No. 20. Milk or House Snake. Page 174. 



AA. Scales keeled. 



B. Anal plate entire, or BB. 



C. Scales 29. No. 17. Pine Snake. Page 171. 



CC. Scales 19. (The Garter Snakes; Thamnophis). Page 141. 



D. Lateral stripe on third and fourth rows of scales. No. 7. Ribbon Snake, 



Striped Garter Snake.. Page 141. 

 DD. Lateral stripe on second and third rows of scales. No. 8. Garter Snake, 



Common. Page 143. 

 BB. Anal plate bifid or divided. 



C. Scales in fewer than 20 rows, or CC. 



D. Scales in 15 to 17 rows, or DD. 



E. Green; tail 1-3 of length. No. 14. Green Snake. Page 162. 

 EE. Brownish (never green); tail not 1-3 length. 



F. No black dots on back; loral plate present. No. 3. Brown Snake. Page 135. 

 FF. Black dots on back; no loral plate. . 



G. Scales in 15 rows. No. 4. Red-bellied Snake. Page 136. 

 GG. Scales in 17 rows. No. 5. Rock Snake. Page 138. 

 DD. Scales in 19 rows. 



E. Spots both above and beneath. No. 6. The Red Snake. Page 140. 

 EE. Stripes but no spots. 



F. Lower row of scales smooth. No. 9. Rigid Queen Snake. Page 150. 

 FF. Scales all keeled. No. 10. Striped Water Snake. Page 150. 



CC. Scales in more than 20 rows. 



D. Snout not fiat, pointed nor keeled, or DD. 



E. Ventral plates fewer than 160. No. 11. Spotted Water Snake. Page 152. 

 EE. Ventral plates more than 200. 



F. Scales in 27 rows. No. 12. Pilot Snake. Page 157. 

 FF. Scales in 25 rows No. 13. Fox Snake. Page 161. 



DD. Snout flat, pointed and keeled. No. 21. Spreading Adder. Page 180. 



(For the key to our species of Crotalidse — Rattlers and Copperheads — see 

 Page 186. 



(c). COLOR KEY FOR PENNSYLVANIA SNAKES. 



1. Without fangs; no pit between eye and nostril. 2. Family 1. Colubridge. 

 With fangs, and pit between eye and nostril. 25. Family 2. Crotalidae. 



2. Body uniformily colored above, A\'ithout other markings. 3. 

 Body with spots or stripes above 8. 



3. Color brown. 4. 



Color greenish or black. 5. ' 



4. Scales not keeled — smooth. No. 1. Carphophiops amoenus (Say). Ground 



Snake. Page 134. 

 Scales keeled — rough. No. 3. Haldea striatula (L.) Brown Snake. Page 135. 



5. End of snout pointed and upturned. No. 21. Heterodon 'platirhinos (Latr.). 



Spreading Adder. Page ISO. 

 End of snout not pointed nor upturned. 6. 



6. Color green or greenish. 7. 

 Color black or bluish black. 6a. 



6a. Belly slaty blue. No. 16. Bascanion constrictor (L.). Black Snake, Page 166. 

 Belly with dark blotches. No. 12. Callopeltis obsoletus (Say). Pilot Snake. 

 Page 157. 



7. Scales smooth. No. 15. Liopeltis vernalis (DeKay). Grass Snake. Page 164. 

 Scales keeled. No. 14. Opheodrys sestivus (L.). Green Snake. Page 162. 



8. Tip of snout upturned. No. 21. Heterodon platirhinos (Latr.). Spreading 



Adder. Page 180. 

 Tip of snout not upturned. 9. 



9. Top of head bright copper-colored. No. 13. Callopeltis vulpinus (B. & G.). 



