ELASMOBRANCHII, Z-lis-mo-hrang'k1-i a subclass of fishes, containing the sharks and rays. The skull is cartilaginous with only su perficial calcifications and no true dermal bones; the gills fixed and shaped like pouches the upper jaw is the pterygo-palatine bar, and the lower jaw Meckel's cartilage, attached to the skull by a large hyo-mandibular element; the exo-skcleton consists of toothlike granular tubercles or spines; and the trunk endoskeleton is cartilaginous. The ventral fins arc far hack and bear claspers in the males; the heart has but one auricle and one ventricle; and the in testine is provided with a spiral valve. The group is nearly coextensive with Cuvier's Chon dropterypia or cartilaginous fishes and the Placoidet of Agassiz, and has received various other names such as Selachii and PLagiostpmi. Cope distinguishes as orders the SeS dsa , which includes all living as well as many ex tinct forms; and the Ichthyotomi, which are exclusively carboniferous and have simple claspers and extensive cranial calcifications.
See -FISH; RAY; SAWFISH; SHARKS; SKATE, etc.
gigantic marine fossil reptiles of the order Sauropterygia, found in cretacean beds. As a living animal it was contemporaneous with Plessosaurus, of the same order, which abounded in the eastern and as a fossil has been found in Europe and New Elasmosaurus had a lizard-like, elongated body, sometimes 45 feet long, flat tened limbs which served as oars, and a long, paddle-shaped tail which assisted its motion through the water. The head was proportion ately small and with the neck performed twist ing motions much like the corresponding parts of the swan. The contents discovered in the body indicate that this sea-saurian lived on other rapacious fish, which it was able to seize with its crocodile-teeth. The fossil has been raised from cretaceous beds in New Jersey and in Kansas.