For nearly half a century geologists have followed with great interest and admiration the discoveries of fossil vertebrate animals in the west of North America. From the early days when western pioneers brought back scattered fragments for study by Leidy, to the seventies and eighties of last century when Cope and Marsh led or encouraged adventurous expeditions to collect fossils in the territories then occupied by hostile Indians, the continual succession of new forms of extinct reptiles, birds, and mammals met with in an unusual state of preservation, excited increasing attention. So remarkable, indeed, were these finds and so sporting was their pursuit, that rivalries arose and passed beyond the state of friendly emulation which is good for real progress. It was thus fortunate for American palæontology that a younger generation of well-trained enthusiastic students was then ready to enter the field, and especially fortunate that their leaders were imbued with a harmonious spirit of co-operation. Among these leaders was the subject of our present biographical sketch, who has perhaps done most by his personal influence to maintain the happy relations which now exist between all workers in vertebrate palæontology in America.

In 1914 I published, in this Magazine, an account of “Some Problematical Structures in the Holectypoida”, indicating therein the presence of certain sunken features on the test-surface of “Pygaster” (Plesiechinus), Coenholectypus, and Discoides. Two series of depressions were described, of which one was wholly sutural in position, while the other was situated on the adoral ambulacral plates, and consisted of more or less sunken tubercles or granules. It is with the latter series of structures that the present paper deals. Although the title “problematical structures” remains appropriate, further work and more refined methods of preparation have made possible a more accurate description of them, and have considerably increased the area of their known distribution. Save for comparisons and passing references, the development of depressions on the tests of the Pygasteridæ and Holectypinæ will not be considered here. In Jurassic times, when these two groups were at their prime (in this country at least), sunken tubercles were in an incipient stage of evolution, and are in consequence very difficult to distinguish from their normal associates. It is therefore safer to deal first with the well-matured structures, as developed in Upper Cretaceous times. Moreover, the condition of preservation, and especially the character of the matrix, of Chalk fossils, make it easier to clean and stain the specimens without much risk of damage to delicate surface features.

In “The North American Crinoidea Camerata”, 1897, Wachsmuth & Springer discussed at length the various modes of partitioning the base, and attempted to give a morphological, if not a physiological, interpretation of the various appearances. In reviewing this part of their work (Geol. Mag., Sept. 1898, pp. 426–428) I contented myself with giving a summary of their views, corrected only in so far as facts of structure were concerned. This summary was reprinted in the Echinoderm volume of Lankester's Treatise on Zoology (1900, pp. 122, 123), although some of the theory involved in it was not in accord with the phylogenetic hypotheses expressed or implied in the taxonomic part of that work. Mr. Herrick E. Wilson has been more critical. He has brought Wachsmuth & Springer's interpretations to the bar of logic, of fact, and of physiological theory, and has found it necessary to replace most of them by a fresh series.

Included in a large series of marine fossils which I collected from the Cisco Beds of Uralian or Upper Coal-measure age at a well-known locality on the west bank of the Salt Creek at Graham, Young Co., Texas, are several fragments of a single very large nautiloid shell. These fragments had lain so long on the sea-floor before they were covered by mud that they have in many cases been much eaten into by sponges and worms, and are covered by adherent organisms, mostly Bryozoa. Attached to them, however, are twenty specimens of the remarkable Brachiopod which forms the subject of this paper. These specimens are in general perfectly preserved, and are easily freed from their surrounding clay by washing with a tooth-brush.