. A descriptive catalogue of the marine reptiles of the Oxford clay. Based on the Leeds Collection in the British Museum (Natural History), London ... Reptiles, Fossil. 148 MAEINE EEPTILES OP THE OXEOED CLAY. with which bone the maxilla has at most a very short union, being separated from it to a large extent by the anterior end of the jugal. The nasals (n.) are very large elements which take a great share in the formation of the upper surface of the rostrum. They meet in suture in the middle line, and in the uncrushed condition were strongly convex from side to side (text-figs. 56, 57) ; in s
. A descriptive catalogue of the marine reptiles of the Oxford clay. Based on the Leeds Collection in the British Museum (Natural History), London ... Reptiles, Fossil. 148 MAEINE EEPTILES OP THE OXEOED CLAY. with which bone the maxilla has at most a very short union, being separated from it to a large extent by the anterior end of the jugal. The nasals (n.) are very large elements which take a great share in the formation of the upper surface of the rostrum. They meet in suture in the middle line, and in the uncrushed condition were strongly convex from side to side (text-figs. 56, 57) ; in some species (e. g. If. superciliosum) their posterior portion is considerably inflated. Anteriorly they narrow to a point and are thrust between the maxilla? to a varying degree, sometimes, as already noted, reaching the premaxillse. At their posterior end they are separated from one another by the wedge-shaped end of the frontal, between which and the prefrontals they send back a process of varying form and length. Beneath the prefrontal they also send back a process, so that the anterior end of the prefrontal is fixed in a deep bay or notch on their hinder end. The lower border of the ventral prolongation unites below with the lachrymal in a straight suture. The. Portion of skull in front of the orbit in Metriorliynchus (?) moreli: A, front wall of orbit; B, side of skull in front of orbit. (E. 3900, i nat. size.) for., lachrymal foramen ; /., jugal; ?., lachrymal; mx., maxilla ; n., nasal; , prefrontal; , suture for frontal; , suture for union with palatine ; t, tubercle in groove in prefrontal. surface of the nasals is sculptured to a degree varying in the different species: usually the sculpture in this region consists of longitudinal ridges which run into one another irregularly. The prefrontal () is a large and solidly constructed bone which in nearly all specimens is so crushed as to appear merely as a flat plate overhanging the orbit. Actually it con
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectreptile, bookyear1910
