OPHIDIA.
(Slow-worm, ,Serpents.) very numerous, proccelian, with a single transverse process on each side ; no sacrum ; no visible limbs.
The order Ophidia, as it is characterized in the system of •Cuvier, requires to be divided into two sections, according to the nature of the food, and the consequent modification of the jaws and teeth. Certain species, which subsist on worms, insects, and other small invertebrate animals, have the tym panic pedicle of the lower jaw immediately and immoveably articulated to the walls of the cranium. The lateral branches of the lower jaw are fixed together at the symphysis, and are opposed by the usual vertical movement to a similarly com plete maxillary arch above ; these belong to the genera Am phisbcota and A nguis of Linnaeus, the latter represented by our common slow-worm. The rest of the Ophidians, including the ordinary serpents and constrictors, which form the typical members, and by far the greatest proportion, of the order, prey upon living animals of frequently much greater diameter than their own ; and the maxillary apparatus is conformably and peculiarly modified to permit of the requisite distension of the soft parts surrounding the mouth, and the transmission of their prey to the digestive cavity.
The earliest evidence of an ophidian reptile has been obtained from the eocene clay at Sheppy ; it consists of ver tebre indicating a serpent of 12 feet in length, the Pakeophis toliapicus. Still larger, more numerous, and better preserved vertebrae have been obtained from the eocene beds at Brackles ham, on which the typhams and P. poreatus have been These remains indicate a boa-constrictor-like snake, of about 20 feet in length. Ophidian vertebrae of much smaller size, from the newer eocene at Hordwell, support the species called Paleryxrhondrifcr and P. dcpressus.t Fossil verte bne from a tertiary formation near Salonica have been referred to a serpent, probably poisonous, under the name of Laophis.f A species of true viper has been discovered in the miocene deposits at Sansaus, South of France. Three fossil Ophidians from the (Eningen slate have been referred to Cutuber «renatus, C'. Ka rgii, and C. Oirenii.