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Show 270 MR. A. SMITH WOODWARD ON [Feb. 16, to the coronoid region. The quadrate bone (qu.) is clearly thrust between the pterygoids as in the last specimen, and its thickened hinder border is preserved. An imperfect impression of the cranial roof (cr.) seems to indicate a narrowing between the orbits. The characteristic operculum (op.), suboperculum (s.op.), and 12 branchiostegal rays (br.) are also imperfectly shown in impression. Of the vertebral centra only fragments are preserved in the abdominal region-nearly all are indicated in impression. The centra are very short and deep in the abdominal region and the anterior half of the tail, but relatively longer more posteriorly. Their sides are marked by fine longitudinal ridges, and the few centra preserved immediately behind the head are much laterally compressed by crushing, as if they were not well ossified. Eighty centra can be counted before they become as long as deep, and the impression of the hinder half of the tail is not quite clear. The neural and hasmal arches are extremely delicate, and much inclined backwards. There are no traces of the pectoral fins; but there are fragmentary remains of the pelvic pair and their supports entirely in advance of the dorsal fin. The latter arises about opposite the thirty-fifth vertebra and show7s seven rays, with uncertain evidence of an additional one in front and behind. The distal bifurcations of the middle rays are preserved. The anal fin, extending about half the total length of the fish, arises nearly opposite the forty-ninth vertebra. Its rays are extremely numerous, but are not sufficiently distinct in the hinder part to be counted; the foremost rays are apparently thickened by the sliding apart of their right and left halves. Along the ventral border of the trunk there is a narrow streak in which a chain of scutes or abnormally developed scales can be recognized on parts of the caudal region (I.). A third specimen in counterpart (Plate XVIII. fig. 3) exhibits the head and the greater portion of the trunk, with an especially conspicuous display of the ventro-lateral row of enlarged scales just mentioned. On one side of the fossil an impression of the cranial roof is distinct (cr.) showing the truncated occiput, the nearly parallel sides of the otic region, and the slender rostral region, but none of the sutures. There is also some indication of an interorbital constriction, but this may possibly be a false appearance due to the crushing of the parasphenoid upon the roof. Traces of the striated suboperculum are distinguishable; and several branchiostegal rays occur on the opposite side of the specimen. The crushed, short, and delicate vertebral centra are distinguishable ; and in the caudal region the almost filamentous neural and hasmal arches are observable, all much inclined backwards, and those at the hinder end of the fossil clearly inclined to the axis of the fish at a much more acute angle than the short supports of the anal fin. The remains of only six rays are shown in the dorsal fin. The pelvic pair are crushed together and imperfectly seen from above or below; about twelve rays can be counted in the patch they form. The precise characters of the enlarged scales of the conspicuous ventro-lateral series (I.) cannot be determined, but some appear to |
