. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 208 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. Physonemus arcuatus M'Coy. (Text-figure 13.) 1848. Physonemus arcuatus F. M'Coy, Ann. Mag. Nat. Hist. (2), Vol. II., p. 117. 1855. Physonemus arcuatus F. M'Coy, Brit. Palaeoz. Foss., p. 638, PI. III., Fig. 29. 1875. DrejHinacanthus revcrsus St. John and Worthen, Pal. Illinois, Vol. VI., p. 456, PI. XIX., Fig. 5 (non Fig. 6). 1883. Physonemus arcuatus J. W. Davis, Trans. Roy. Dublin Soc. (2), Vol. I., p. 367, PI. XLVII., Fig. 8. 1883. Physonemus falcatus St. John and Worthe
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 208 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. Physonemus arcuatus M'Coy. (Text-figure 13.) 1848. Physonemus arcuatus F. M'Coy, Ann. Mag. Nat. Hist. (2), Vol. II., p. 117. 1855. Physonemus arcuatus F. M'Coy, Brit. Palaeoz. Foss., p. 638, PI. III., Fig. 29. 1875. DrejHinacanthus revcrsus St. John and Worthen, Pal. Illinois, Vol. VI., p. 456, PI. XIX., Fig. 5 (non Fig. 6). 1883. Physonemus arcuatus J. W. Davis, Trans. Roy. Dublin Soc. (2), Vol. I., p. 367, PI. XLVII., Fig. 8. 1883. Physonemus falcatus St. John and Worthen, Pal. Illinois, Vol. VII., p. 252, PI. XXIV., Fig. 6. 1883. Drepanacanthus recersus St. John and Worthen, Ihid., p. 253, PI. XXIV., Fig. 5. 1899. Physonemus stellatus J. S. Newberry, Monogr. U. S. Geol. Surv., Vol. XVI., p. 200, PI. XXL, Fig. 12. 1902. Physonemus arcuatus C. II. Eastman, Bull. Mus. Comp. Zo6\., Vol. XXXIX., p. All of the spines referable to this species which have been previously figured are im- perfect in this respect, that the superficial ornamentation has been very largely de- nuded, and the denticles along the concave margin either worn or broken away, thus obscuring their true relations. Although the example shown in the adjoining Text- figure has been somewhat injured, its gen- eral outline is well displayed, and enough of the ornamentation remains to leave no doubt as to its identity with the type species of this genus. The double row of striated denticles bordering the concave margin is fully as prominent as in typical examples, although abrasion has reduced many of the tubercles in size. One of the latter ife represented seven times the natu- ral size in the figure to the left of the spine. Owing to the worn condition of the basal portion, it is not apparent to what depth the spine was inserted in the integument, but from some other speci- mens the writer has seen it is probable that it was not deeply implanted. There Fig. 12. Physonemus arcuatu
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