Fig. 9. The everted left hemipenis of Conophis vittatus (UMMZ 82650). × 5.
The everted hemipenis reaches posteriorly to the eighth subcaudal scale. The sulcus bifurcates at the third subcaudal scale. The situation is similar in situ (Cope, 1895:pl. 28, fig. 2).
There are no apparent hemipenial differences among the species of the genus Conophis. As can be seen in the above description, the hemipenis of C. vittatus is less bilobed and has a more pronounced disc at the apex than the others. The hemipenis of C. lineatus concolor is most bilobed, but has the smallest apical disc. The other species and subspecies vary widely within these extremes.
Conophis eats mostly small lizards, especially Cnemidophorus. In México Conophis occurs in semi-arid habitat where Cnemidophorus is common. A specimen each of Conophis vittatus and C. lineatus lineatus were obtained while I was collecting Cnemidophorus. The only record of Conophis having fed on a warm-blooded vertebrate was obtained in the course of this study, when I recovered from the stomach of a Conophis lineatus concolor (CNHM 36299) from Chichén Itzá, Yucatán, a heteromyid rodent (Heteromys gaumeri).
Ralph Axtell (personal communication) observed Conophis actively searching for food at dusk. His observations were made near Tehuantepec, Oaxaca, and the snakes were seen to chase lizards of the genus Cnemidophorus. Near Alvarado, Veracruz, in the late afternoon, I watched a Conophis lineatus lineatus follow a lizard into a hole.
Mittleman (1944:122) presents the only discussion of the mode of feeding of a captive specimen of Conophis lineatus ssp. When presented with a Thamnophis slightly smaller than itself, the Conophis struck, and within eight minutes immobilized the Thamnophis. Within one-half hour the Thamnophis was swallowed. Three days later the Conophis ate another Thamnophis, though still distended from its first meal; nine days later it ate a Storeria. In the course of several months, the Conophis ate various toads and hylids and two more Storeria. Apparently members of the genus Conophis do not constrict their prey, but rely upon a combination of loss of blood and action of the venom to completely immobilize their prey.
Ditmars (1931:pls. 26-27) showed three photographs of "Conophis lineatus" (actually Conophis pulcher) ingesting another snake, identified by him as a young Ophis (= Xenodon) colubrinus.