MICHIGAN ACADEMY OF SCIENCE. 113 



ANALYTICAI- KEY TO THE GENERA. 



Serpents with the n^axillary fixed to the internasal and preniaxillary : a pubis is pres- 

 ent: usually of subterranean habits. The Blind Snakes. Catadonta, A. 



Serpents with maxillary bone horizontal, in contact with the premaxillary, and pro- 

 vided with solid teeth. The Harmless Snakes — Asinea, B. 



Serpents with channeled maxillary fangs and loreal pit. The Pit Venomous Snakes. — 

 Solenoglypha, C. 



Serpents with colubriform jaws, the anterior maxillary teeth grooved or perforated: 

 pupil vertical. The Pitless Venomous Snakes. Proteroglypha, D. 



A . Catodonta, — Kat-o-don-ta. 



Serpents -nath head slightly depressed: rostral large: snout rounded, overlaping the 

 lower jaw. Fam. 1. Glanconiidae. 



B. Asinea — As-i-ne-a. 



Serpents without premaxillary: with supraoculars and postoculars: peropods. Fam. 2. — 

 Boidae. 



Serpents without supraoculars and without cronoid bones: spur like appendages are 

 present. Fam. 3. Chrinidae. 



Serpents without loreal pit, upper surface of head covered with plates. Fam. 4 — 

 Colubridae. 8. 



C. Solenoglypha — Sol-e-nog-li-fa. 



Serpents with poison fangs in front part of mouth: with a deep loreal pit between the 

 eye and nostril. Fam. 5.— -Crotalidae. 9. 



D. Proteroglypha — Prot-e-rog-le-ja. 



Serpents with erect poison fangs in front part of mouth: loreal pit wanting: jaws not 

 dilatable: pupil vertical. Fam. 6 — Elapidae. 



Note. — No representatives of families one, two, three and six, have been found in Mich- 

 igan. 



Fam. 4, Colubridae — Ko-lu-bri-de. 



I. Dorsal scales keeled, a. 



a. Anal plate entire, b. 



b. Dorsal scales in 15-17 rows. — Storeria, 114. 



b. Dorsal scale rows not exceeding 23; two nasals. — Eutaenia, 114. 



b. Dorsal scale rows exceeding 23. — Pityophis, 115. 

 a. Anal plate divided, c. 



c. Loreal absent, rarely present. — Storeria, 114. | 



c. Loreal and one or more preoculars presented. 



d. Dorsal scale rows 17 or fewer. — Cyclopliis, 116. 



d. Dorsal scale rows 19 or more, e. , 



e. Head plates normal f. 



f. Dorsal scales in 19-33 rows, all keeled. — Natrix, 116. 



f. Dorsal scales in 23-35 rows, some smooth. — Coluber, 117. 

 e. Head plates not normal, g. 



g. Muzzle produced; dorsal scales in 23-27 rows. — Heterodon.^llS. 



II. Dorsal scales smooth, h. 



h. Preocular absent ; lorealocular present, i. 



i. Dorsal scales in 13 rows; one post ocular. — Carphophiops, 118. 



h. Preocular usually one, rarely two, j. 



j. Anal plate divided, k. 



k. Dorsal scales in 15 rows; preoculars 1-2: color green. Liopeltis, 118. 



k. Dorsal scale rows not exceeding 25; superior lablials 7. Ophibolus, 118. 



k. Dorsal scale rows 25 or more; superior labials (7), 8-9. Coluber. 117. 



j. Anal plate entire. 1. 



1. Dorsal scales in 21-25 rows; loreal 1, temporals (1), 2, 2, (3). Ophibolus, 118. 



n. Preoculars usually two, m. i;k..ai. 



m. Anal plate divided, n. 



n. Usually with a cervical ring; rather small. Diadophis, 119. 



n. Without cervical ring; body elongated. Bascanium, 119. 



15 



