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Show 350 MR. A. SMITH WOODWARD ON NEW FISHES [Apr. 15, measurement is contained scarcely six times in the total length. caudal pedicle is also much less robust in this immature Purbeckian fish than in the typical species from the French Lithographic Stone. Genus STROBILODUS. [A. Wagner, Abh. k.-bay. Akad. Wiss., Cl. ii. Bd. vi. 1851, p. 75.] STROBILODUS PURBECKENSIS, sp. nov. (Plate XXIX. fig. 4.) A single example of the head and pectoral arch, with a portion of the abdominal region, exposed from the right lateral aspect, indicates the occurrence of a small species of Strobilodus in the Purbeck beds of Swanage. The specimen is shown of the natural size in Plate X X I X. fig. 4, and is unfortunately too much crushed to exhibit many details of its osteology. It adds, however, a few new points to previous observations on the genus. Head and Opercular Apparatus.-The head must have been originally somewhat compressed from side to side, longer than deep, and with a pointed snout. The cranium is narrow and elongated, with a well-developed parasphenoid (pas.); and the cranial roof exhibits no ornamentation, being only sparsely pitted. The premaxilla (pmx.) is evidently short, though much broken, and the maxilla (mx.) is relatively long and nanow. This element is robust and has a somewhat wavy dentiuerous border, its anterior two thirds forming a gentle convexity, this passing backwards into a short concavity, and becoming convex again at the hinder end. The mandible (md.) is also long and narrow, deepest at its articulation, and gradually tapering to its pointed extremity. The mandibular suspensorium is very oblique, but its elements are obscured by thin postorbital membrane bones, which seem to have attained considerable proportions and are externally unornamented. The branchial arches and pectoral arch are also covered by the crushed remains of the opercular bones, which likewise exhibit a smooth outer surface. The preoperculum (p.op.) is long, narrow, and gently curved, without a distinct inferior limb. Dentition.-A single series of teeth, of large size and well spaced, occupies the whole of the margin of the month above and below. Each tooth is fused with the supporting bone, has a large pulp-cavity, is somewhat tumid at its base, and ends upwards in a long, slender, tapering apex; there is also a characteristic median longitudinal depression on the outer aspect of the tumid base of all the principal teeth. The teeth vary somewhat in size, those of the maxilla being largest in the middle of the great convexity, smallest in the concavity, and relatively long, slender, and closely arranged on the hinder convexity. In the mandible, the largest examples are in the middle of the ramus. There are not less than twenty-eight teeth in the upper jaw and twenty in the lower. Vertebral Column.-The remains of the vertebrae (v.) are seen in the form of narrow, though robust rings, either complete or nearly so, somewhat angulated, and apparently with slight tuberosities for |