1028 
Reithrodon, 80. 
Reithrodontomys, 77. 
Rheithrosciurus, 3. 
Rhipidomys, 72. 
Rhizomys, 99. 
Rhombomys, 31. 
Rhynchomys, 25. 
Romerolagus, 158. 
Saccostomus, 44. 
Scapteromys, 82. 
Schizodon, 125. 
Sciuropterus, 12. 
DR. J. W. GREGORY ON THE CLASSIFICATION 
Siphneus, 98. 
Sitomys, 71. 
Sminthus, 113. 
Spalacopus, 126. 
Spalax, 101. 
Spermophilus, 7. 
Steatomys, 37. 
Synaptomys, 94, 
Synetheres, 146. 
Tachyoryctes, 100. 
Tamias, 6. 
Thomomys, 103. 
[Dee. 15, 
Thryonomys, 141. 
Triaulacodus, 141. 
Trichys, 144. 
Tylomys, 73. 
Typhlomys, 21. 
Uromys, 58. 
Vandeleuria, 48. 
Vesperimus, 71. 
Xenomys, 89. 
Xeromys, 23. 
Xerus, 4 
Zapus, 114. 
Sciurus, 5. 
Thrichomys, 133. 
Sigmodon, 75. 
Thrinacodus, 130. 
7. On the Classification of the Palzozoic Echinoderms of 
the Group Ophiuroidea. By J. W. Grecory, D.Sc., 
F.Z.8. 
[Received November 5, 1896.] 
For fifty years after Forbes, in 1840 [3. p. xiv], proposed to 
rank the Ophiuroidea as one of the classes of Echinoderma they 
were divided into two groups—the Ophiure and Euryale of 
Joh. Miiller, the Ophiuride and Haeyalide of Th. Lyman. In 
1867 Dr. Axel Ljungman [7] divided the first group into six 
families (the Ophiodermatidx, Ophiolepidide, Amphiuride, Ophio- 
myxide, Ophiocomide, and Ophiothricide), 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 Ophiuride 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, palzontologists 
were naturally in a worse state ; for the anatomical characters of 
the fossil Ophiurids had been in but few cases satisfactorily deter- 
mined. We have only to refer to Wright’s introduction to the 
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 Paleozoic Ophiurids ; but the author 
