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Show 1034 DR. J. W. GREGORY ON THE CLASSIFICATION [Dec. 15, Type species.-Bundenbachla beneckel, Stiirtz. Remarks.-The diagnosis of this genus is based on specimens in the British Museum received from Herr Stiirtz. The diagram (fig. 4) has been prepared from specimen B.M. No. E 3495. Fig. 4. Bundenbachla: arm-structure. Bundenbachla differs from Protaster by the irregular nature and soft plating of the disc, by the presence of spine-bearing plates attached to the adambulacral ossicles, and by the different form of the ambulacral ossicles. Family 2. PAL^OPHIURID-E. Diagnosis.-Lysophiurae in which the ambulacral ossicles are long and bar-shaped, with the longer axis parallel to the arm. Remarks.-This family agrees with the Protasteridae in not having the ambulacral ossicles of each segment placed opposite one another. It differs by having the ambulacral ossicles longer than wide, and never divided transversely by muscular depressions. The ambulacral ossicles are either bar-shaped or thickened to a subquadrate form. They are never boot-shaped. Genus 1. PAL^EOPHIURA, Stiirtz, 1890 [16. p. 233]. Biagnosls.-Palaeophiuxidse with the disc surrounded by rod-shaped marginal ossicles. The ambulacral ossicles are rods lying parallel to the arm. Distribution.-Lower Devonian, Bundenbach. Type species.-Palceophlura simplex, Stiirtz. Genus 2. STURTZURA, nov. gen. Biagnosls.-Palaeophiuridao having thick, subquadrate, ambulacral ossicles and narrow adambulacral plates. The disc is fragile, and its plates are small, and thin: it has no marginal plates. The mouth-frames are narrow and separate. Bistribution.-Silurian, England and Australia. Type species.-Sturtzura brislngoldes (Gregory), 1889 [5]. Remarks.-This genus differs from Palceophlura, as the ambulacral ossicles are thick aud subquadrate, instead of being in the |