text: Solenoglyph Solenoglyphous snakes (pipe grooved) have the most advanced venom delivery method of any snake. Each maxilla is reduced to a nub supporting a single hollow fang tooth. The fangs, which can be as long as half the length of the head, are folded against the roof of the mouth, pointing posteriorly.  The skull has a series of interacting elements that ensure that the fangs rotate into biting position when the jaws open.  Solenoglyphous snakes open their mouths almost 180 degrees, and the fangs swing into a position to allow them to penetrate deep into the prey.  While solenoglyph venom is typically less toxic than that of proteroglyphs, this system allows them to deeply inject large quantities of venom. This form of dentition is unique to vipers.
  Exceptions
  A few snakes do not conform to these categories.  Atractaspis is solenoglyphous but the fangs swing out sideways, allowing it to strike without opening its mouth, perhaps allowing it to hunt in small tunnels. Scolecophidia (blind burrowing snakes) typically have few teeth, often only in the upper or lower jaw.
  Informal or popular terminology
  Common names for the various types of snake dentition originate largely from older literature, but still are encountered in informal publications. Aglyphous snakes are commonly called fangless; opisthoglyphous snakes rear-fanged or back-fanged; and both Proteroglyphous and Solenoglyphous snakes are referred to as front-fanged.
  Taxonomic key of skull modifications
  Modifications of the skull in the European genera:
  I. Quadrate articulating with the cranium, supratemporal absent; mandible much shorter than the skull, with coronoid bone; maxillary small, on lower aspect of cranium; pterygoids not extending to quadrate; nasals forming long sutures with the premaxillary, prefrontals, and frontal: Typhlops.