Page:The American Cyclopædia (1879) Volume X.djvu/365

 LEPIDOSIREN 359 LEPIDOSIREX, a vertebrated animal, possess- ing characters of both fishes and reptiles, and alternately referred by naturalists to one or the other of these classes. This animal was dis- covered by Dr. Natterer in the river Amazon in 1837, and was referred by him and Fitz- inger to this genus, considered by them as be- longing to the fish-like or perennibranchiate reptiles. Prof. Owen ("Linnsean Transac- tions," vol. xviii., and "Proceedings of the Linnsean Society," April 2, 1839) had recorded this same paradoxical animal, in his MS. cata- logue of the museum of the college of surgeons (1837), as a new genus of abdominal malacop- terygian fishes, under the name of protopterus; he afterward made this family of sirenidce the type of a distinct order of fishes, the protop- teri (the sirenoidei of Mtiller) ; he referred it to fishes on account of its scaly covering and of its nostrils not communicating with the mouth, and to the abdominal malacopterygians from its soft and rudimentary fins, indicating a transition from the abdominal to the apodal families, and for various other anatomical rea- sons. The skeleton is partly osseous, partly cartilaginous; the body is fish-like in form, and covered with cycloid scales ; the pectorals and ventrals are mere jointed flexible rays ; the bodies of the vertebra? remain in the em- Lepidosiren. bryonic state of a continuous chondro-gelati- nous cord, though many other parts of the skeleton are well ossified. This transitional state between the embryonic condition of ossi- fication of the vertebral centre and that of or- dinary bony fishes, was common in the ganoid fishes, not one of which in the Silurian or De- vonian epochs, according to Agassiz, had a vertebral centrum. There are 36 pairs of ribs, encompassing about one sixth of the abdominal cavity ; immediately in front of the pectorals there is a vertical branchial opening ; on the intermaxillary bones are two long, slightly curved, slender, acute teeth, on the upper jaw on each side a dental plate divided into three cutting lobes, and on the lower jaw a similar single plate whose lobes fit into the intervals of the upper, fitted for minute division of food ; the tongue is well developed, the pharynx with a small valve-protected opening, the gul- let short and narrow, the stomach thick, sim- ple, and straight, the liver of good size with gall bladder, and the straight intestine with an internal spiral fold ; there is neither pancreas nor spleen. The respiratory organs consist of branchiae, with a double elongated air bladder resembling the cellular lungs of a reptile ; the branchial sac is large, and the gills are support- ed on four arches on each side, two additional arches offering no trace of gills, there being five intervals for the passage of water into the pharynx; the nasal cavities open into the mouth (this is denied by Owen), and the laryn- geal opening leads to the honeycombed air blad- ders or lungs, which are behind the kidneys and internal reproductive organs ; the kidneys are long and narrow, the ureters and the genital ducts opening into the cloaca ; the heart, in a strong pericardium, has a single ventricle, a sin- gle imperfectly divided auricle, and an arterial bulb, a large part of the blood in the adult be- ing sent to the air bladders for purification. The. eyes are small and adherent to the skin, which passes over them without forming any projection, and the lens is small and spherical ; there is no trace of tympanic cavity nor Eus- tachian tube. The scaly covering, soft fin rays, characters of the spinal canal and cord, mucous ducts and lateral line, peculiarities of the cranial and jaw bones, intestinal spiral valve, absence of spleen and pancreas, single auricle, the nasal sacs opening only externally (the last denied by many), and the articulation of the scapular arch to the occiput, prove, according to Owen, that the lepidusiren is a fish, and not a batrachian, forming a con- necting link between cartilaginous and soft- rayed fishes, and coming in this class the near- est to the perennibranchiate reptiles. The L. paradoxa (Natterer), from the morasses of the river Amazon in Brazil, attains a length of about 3 ft. ; when the water dries up, they plunge under the mud; the food is said to consist of vegetable matters. The L. annec- tens (Owen), from the river Gambia and also the Mozambique <?oast, is a smaller species, rarely more than 2 ft. long. In the "Proceed- ings of the Zoological Society of London " for Nov. 11, 1856, Mr. J. E. Gray advocates the batrachian nature of the lepidosiren, three specimens of which were brought alive from Africa, enclosed in balls of hardened clay in which they remained torpid during the eight months of the dry season; they were on exhibition at the crystal palace at Syden- ham for a considerable time, and one for several months. From the account there given it appears that this animal can move with considerable rapidity forward and up- ward by means of its tail, which is surround- ed by a membranous expansion like a conflu- ent dorsal and anal fin. The pectoral limbs are elongated and margined behind with a narrow membrane, the ventral having a similar edging in the middle of the outer side ; they are very mobile and flexible, and are used more like feet than fins, supporting the body about two inches from the bottom, and also serving to direct its motions ; the two processes on each side over the pectorals, considered as external gills by some, he regards as a portion of the anterior limb, as they possess no peculiar vas- cular structure ; the movements are much more like those of the water salamanders than of eel-shaped fishes. The mucous pores on the