DIP'NOI (Neo-Lat. lima. pl.. front Gk. 31, di-, double + Irvefv, to breathe, referring to their breathing through the gills and the lungs). The lung-lishes. a group of fishes, by some zoologists regarded as an entirely separate class of vertebrates. They were more numerously represented in past ages than now, when their only living representatives are the genera t'eratodus (see P.AHRAAI N11.1) l'rotop terus. and Lepidosircit I SIP Their chief peculiarity is in the organs of respiration, since, in addition to piscine gills, they have either one or OA 0 lungs proper to breathing air. They have bony scales, but the skeleton is cartilagi nous, and thus described by Parker and Ilasm/ 11: "The notoehord i. persistent, and the cranium rsee Plate) consists of a of cartilage with little ossificati , but with the addition of a mordwr of membritne bones, the skull is (tato. static. the lower jaw ;till/milting tiith a palatm quadrate process 1 pal), eor•esponding to the 1.111;10).9u Ideate of the dogfish, hut immovable fixed to the side of the skull. There are four or leaoyluu1 The gills are covered user by ;III operetilmil. The structure
f the paired tins is on a totally different plan from that of any other lieinl fish, The fin, pectoral or pelvic, as the may is or very long and narrow, and the skeleton con sists of a central axis in the form of a slender, tapering, jointed rod of cartilage:, with a row of smaller jointed rods of cartilage on either side of it, This form of tin-skelotott, which occurs in certain groups of fossil fishes, as well as in Dipnoi, has been termed the archipterygium." In respect to the structure of the soft parts, it may be noted that a cloaca is present, and the intes tine cont;ains at spiral valve; the heart is more complicated and highly developed than in ordi nary fishes, and a pulmonary artery and vein exist. The special interest in this group arises from the belief that it anciently gave' rise to the class of amphibians. Consult: Cope. Origin of the Fittest New York. 1SS6) id., But rachia of North- America (W a:hiugton, 1S99) ; t;adow, (London, 1001). See STECOCEPHALIA; and Plate of DIrsor AND Cut