LIST OF PLATES. 
Prats I. 
Fig. 1. Phrynonae eutropis, Blgr., p. 22. 
2. Coluber janseni, Blkr., p. 57. 
Upper and side views of head and neck. 
Prats II. 
Spilotes megalolepis, Gthr., p. 24. 
Upper, lower, and side views of head and neck. 
Prats III. 
Fig. 1. Coluber frenatus, Gray, p. 58. 
. Leptophis occidentalis, Gthr., p. 111. 
nigromarginatus, Gthr., p. 112. 
Upper view of head and anterior part of body, and 
side view of head. 
Prats IV. 
Fig. 1. Dendrophis bifrenalis, Blgr., p. 80. Upper view of head 
and neck. 
la. ——. Side view of head. 
1b, —— Side view of middle of body. 
2. grandoculis, Blgr., p. 84. Upper view of head 
and neck. 
2a. Side view of head. 
