. Bulletin. Natural history. RUSSELL: AMERICAN MOSASAURS 161 Type. Specimen not located, originally ". . from Burlington N. J.," (Cope, 1869-1870, p. 196) collected by L. T. Type specimen includes a quadrate, cranial fragments and dorsal vertebrae (Cope, 1869-1870, p. 196). Distribution. Navesink Formation or younger Cretaceous, New Jersey. Additional References. Leidy, 1865a, pi. 7 figs. 2-3, ?8, ?9-ll. Cope, 1868b, p. 734; 1869-1870, pp. 189, 198, 210. fig. 48(3), ?pl. 5 fig. 4, pi. 11 fig. 6; 1875, pp. 269, 270, 272, pi. 37 fig. 12. Marsh, 1872b, p. 455. Merriam, 18
. Bulletin. Natural history. RUSSELL: AMERICAN MOSASAURS 161 Type. Specimen not located, originally ". . from Burlington N. J.," (Cope, 1869-1870, p. 196) collected by L. T. Type specimen includes a quadrate, cranial fragments and dorsal vertebrae (Cope, 1869-1870, p. 196). Distribution. Navesink Formation or younger Cretaceous, New Jersey. Additional References. Leidy, 1865a, pi. 7 figs. 2-3, ?8, ?9-ll. Cope, 1868b, p. 734; 1869-1870, pp. 189, 198, 210. fig. 48(3), ?pl. 5 fig. 4, pi. 11 fig. 6; 1875, pp. 269, 270, 272, pi. 37 fig. 12. Marsh, 1872b, p. 455. Merriam, 1894, p. 37. Williston, 1898b, p. 207. Hay, 1902. p.'472 (L. laficaudus). Gilmore, 1926. p. 191, pi. 62 fig. 5. Miller. 1955. pp. 905, 909. Referred Specimens. AMNH nos. 1382, 1430, 2304. YPM nos. 312 (P. copeanus), ?411 (L. laticaudus), 445 (P. fraternus). Diagnosis. Anterior zygopophyses of cervical and anterior dorsal vertebrae separated from synapophyses by longitudinal sulcus, lateral surface of neural arch smooth. Func- tional zygopophyses probably end near center of dorsal series. Discussion. The quadrate belonging to the type of 71/. depressus, figured by Cope (1869-1870, fig. 48(3), pi. 11 fig. 6), has a large suprastapedial process with parallel sides, as is the case in all members of the Plioplatecarpinae. It also has a relatively thick tympanic ala and, in medial aspect, resembles the quadrate of Plioplatecarpus more closely than that of any other genus of mosasaur. The New Jersey quadrate cannot be confused with Plalecarpus because, lying posterior to the ventral margin of the stapedial pit, there is a prominence that nearly closes o5 the stapedial notch from below, which is lacking in the latter genus. The blunt termination of the dentary immediately anterior to the first dentary tooth and the bicarinate, medially recurved and vertically striated teeth in the type speci- men of M. copeanus all strongly support die inclusion of this species in the Plioplate-. Text-fi
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