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Show 1028 DR. J. W. GREGORY ON THE CLASSIFICATION [Dec. 15, Reithrodon, 80. Reithrodontomys, 77. Rheithrosciurus, 3. Rbipidomys, 72. Rhizomys, 99. Rhombomys, 31. Rhynchomys, 25. Romerolagus, 158. Saccostomus, 44. Scapteromys, 82. Schizodon, 125. Sciuropterus, 12. Sciurus, 5. Sigmodon, 75. Siphneus, 98. Sitomys, 71. Sminthus, 113. Spalacopus, 126. Spalax, 101. Spermophilus, 7. Steatomys, 37. Synaptomys, 94. Synetheres, 146. Tachyoryctes, 100. Tamias, 6. Thomomys, 103. Thrichomys, 133. Tbrinacodus, 130. Thryonomys, 141. Triaulacodus, 141. Trichys, 144. Tylomys, 73. Typhlomys, 21. Uromys, 58. Vandeleuria, 48. Vesperimus, 71. Xenomys, 89. Xeromys, 23. Xerus, 4. Zapus, 114. 7. O n the Classification of the Palaeozoic Echinoderms of the Group Ophiuroidea. By J. W . G R E G O R Y , D . S C, F.Z.S. [Received November 5, 1896.] Por fifty years after Porbes, in 1840 [3. p. xiv], proposed rank the Ophiuroidea as one of the classes of Echinoderma they were divided into two groups-the Ophiurae and Euryalae of Job. Midler, the Ophiuridae and Euryalidae of Th. Lyman. In 1867 Dr. Axel Ljungman [7] divided the first group into six families (the Ophioderrnatidaa, Ophiolepididae, Amphiuridae, Ophio-niyxidee, Ophiocornidse, and Ophiothricidse), but Mr. Lyman [10], in his description of the Ophiurids collected during the ' Challenger' Expedition, made no use of family divisions. He simply divided the Ophiuridae into three groups, of which the first two were unnamed, and the third was merely described as comprising "Astrophyton-like Ophiuroids." Hence Lyman's great monograph, the richest mine of information in the whole range of literature on the Ophiurids, did not contribute so much to their classification as to our knowledge of their anatomy. As neontologists were in difficulties owing to the lack of a satisfactory arrangement of the recent species, palaeontologists were naturally in a worse state ; for the anatomical characters of the fossil Ophiurids had been in but few cases satisfactorily determined. W e have only to refer to Wright's introduction to tbe British Jurassic Starfish [20], or to Liitken's [9. pp. 70-75, 78] heroic attempt to improve the generic nomenclature of the Neozoic Ophiurids, to see how unscientific the existing systems were. In 1886 and 1890, Herr B. Stiirtz, in two important memoirs [15,16], described the anatomy of several genera from the Devonian of Bundenbach, in the Bavarian Pfalz. The fossils are pseudomorphs in iron pyrites ; owing to the exceptional preservation of the specimens and the skill and patience with which Stiirtz dissected them from their clay-slate matrix, their anatomical structure was well displayed. Stiirtz's two papers are a great advance on any previous work dealing with Palaeozoic Ophiurids ; but the author |
