1912] Ditmars: Feeding Habits of Serpents 221 



mammalian prey. Dendrophis is a strictly arboreal genus and the 

 food appears to be confined to tree-lizards and such batrachians as 

 can be found among the branches; the food animals of the latter type 

 consist of small species of Hyla. 



Passing through the maze of Colubrine genera, it is possible to 

 select another group of related forms, a number of representatives of 

 which have been under observation. These are the genera Coronella, 

 an Old World genus of six species; Ophiholus, the King Snakes of 

 North America, Mexico and Central America (seven species); Dia- 

 dophis, the Ring-Necked Snakes of the United States and Mexico 

 (three species); Rhinochilus, the Sharp-nosed Snakes of the United 

 States and Mexico (three species) ; and Cemophora, the Scarlet Snake 

 of the southeastern United States. Close relationship is clearly 

 indicated by well-defined feeding traits. All of the species are pro- 

 portionately powerful constrictors; and all are oviparous. Without 

 exception, they exhibit cannibalistic habits in feeding upon other 

 serpents and lizards. With the exception of DiadopMs, which is 

 apparently a degenerate off-shoot of Ophiholus, the species of the 

 entire group also feed upon small mammals. A peculiarity of these 

 snakes is their utter lack of interest in the batrachians, the frogs, 

 toads and salamanders, although evincing a marked appetite for 

 cold-blooded prey in the shape of other reptiles. In this habit, the 

 rather insignificant species of DiadopMs are exceptions as they feed 

 largely upon earthworms and salamanders, although showing rela- 

 tionship to the ancestral group in also feeding upon other small 

 snakes — a rather unusual trait for a very small serpent. One trait 

 of notable specialization away from the parent group as exhibited by 

 DiadopMs is shown in the retention of the eggs until the embryos are 

 well developed. Thus, with an oviparous species, the young hatch 

 within about thirty days after the eggs are deposited, opposed to the 

 eight or ten weeks required for the incubation of the eggs of the other 

 species involved. As before noted, we may trace among the ovip- 

 arous or viviparous Colubrine serpents a rather definite indication 

 of preference for warm or cold-blooded prey. This indication is 

 again evident with the present group. Coronella, OpMholus, RMn- 

 ocMlus and Cemophora are composed of species depositing eggs with 

 thread-like embryos and requiring a considerable period for incuba- 

 tion. All of the species feed to a considerable extent upon small 

 mammals. With DiadopMs, branching from these forms, and 

 restricting the food to cold-blooded creatures, there is the tendency, as 



