diamondback

Short definition from Wiktionary

Noun

1. 1
   Either of two species of rattlesnake having a diamond pattern on the back: Crotalus adamanteus, found in the southeastern United States, and Crotalus atrox, found in the southwestern United States and northwestern and central Mexico.
2. 2
   The saltmarsh terrapin of the Atlantic coast (Malaclemys terrapin).