Page:Synopsis of the Exinct Batrachia and Reptilia of North America. Part 1..pdf/66

 60—B TIIE EXTINCT BATRACHIA, REI'TILIA 31 31 Length. .075 Inner, .005 Proximal expanse, outer measurement, .052 The portion of the pelvis preserved consists of the proximal halves of left ilium and ischium, the anterior portion of the latter being broken away. This fragment is not Dinosaurian; the longitudinal expansion forbids the reference of the ilium as the isehiopubis of a Dicynodont, and the ischium is too different to be regarded as the scapula of a Belodont. It presents a broad shallow concavity as acetabuium, which on the inner face is grooved and ridged at the inferior margin, as though united to the ischium by suture. This is well shown in Emmons' figures of the same bone of another species, in North Amer. Geology, Pl. VI. The upper plane of this element is abruptly curved backwards and then broken away. The supposed ischium presents a marked acetabnlar articular face at its posterior connection with the ilium. Its posterior margin is much thickened, and becomes decurved towards the symphysis, which is lost. It sends a limb anteriorly along the line of union with the ilium, and apparently terminates in a narrow obtuse ex-tremity with rugose margins. Its supposed obtruator margin is thickened along this process; the main body of the bone is flattened at a strong angle with the posterior margin, and turned away anteriorly like the ilium of a Dicyno-dont, and includes an incomplete oval foramen with the acetabular process. The two pelvic elements are crushed nearly into one plane. Length of fragment. 0.167 Width ischium at foramen, .055 C ilium to posterior process, .0715 Thickness " distally, .021 • iliac suture of ischium, .092 The mode of attachment of the pubis is not indicated in this specimen, but it was evidently quite different from that in the Crocodilia. The femur is that of the left side; it is perfect, except that the portion usually supporting the third trochanter is broken out; say two inches. The head is Crocodilian, i. e., without neck and compressed in one plane. Its extrem-ity is sightly convex inwards, the inner extremity thickened, convex and decurvcd; the extero-posterior thinned and curved backwards slightly. The margin continued from the latter is therefore thinned, though obtuse edged, and encloses a wide shallow groove with the inner, thickened margin. There are no distinct trochanters. The shaft is quite slender, obliquely spherical triangular in section, with an inner ridge in front, and outer behind. The medul-lary cavity is very small. At the distal third the shaft is flattened antero-posteriorly. The trochlear groove is wide and shallow, and the condyles project less posteriorly than is usual; they have, however, been under considerable pressure. The inner is wider and shallower, the outer narrower and deeper. Their extremital faces are separated by an open notch. The ,fibula is a long slender bone, having a slight sigmoidflexure, and ridges twisted round the flattened shaft. The extremities are more flattened, both in the same plane; the proximal is broken away; the distal is obtuse, one end terminating in a point; the surface rugose. Length femur, restored, Diameter head, antero-postcrior, •• " transverse (greatest), shaft at middle, eondyles, transverse, Its form is Lacertilian. 0.34 Diameter condyles, inner, fore and aft, 0.09 Length fibula, broken, 0.044 Diameter perfect extremity, 0.045 imperfect 0.083 " shaft, .045 0.045 0.24 0.035 00.002452 What is doubtfully referred as a distal phalange, resembles that ascribed to a species of the genns by Meyer, but as I cannot find lateral grooves, and the proximal articulations are concealed by matrix, it may not be such. One lateral margin is obtuse, the other acute; body- thhmed out to tip, flat in cross section below, concave in longitndinal, as wide distally as proximally. 31. .3r. Length, .035 Depth proximally, .0165 Width distally, .017 Surface striate-rugosc; lines of the upper surface converging toward a median point from the base. Ssveral more or less broken, and one complete rib are prescn-ed. The two heads are distinct. The perfect rib