CRINOID GENUS SCYPHOCRINUS 21 



coinciding at the plate angles, with or without folding of the surface (PI. VI, 

 figs. 18, 19). The fine, low ridges which cause the striation of the surface 

 terminate in the marginal crenulae, and are apparently formed by the contin- 

 uous growth of the crenulae during lateral increase of the plates. The internal 

 folds have no relation to the external folds or the ligament fossae, and their 

 purpose is doubtful. 



The stem facets of Scyphocrinus are circular, the contact area narrow, 

 sloping gradually into the ligament fossa, with radiating crenulae passing nearly 

 to the center (PI. V, figs. 2-5). In the root bulb (Camarocrinus), the plate 

 facets are slightly concave, and the crenulae radiate outward from the central 

 axial canal (text-fig. 2). 



THE AMERICAN SPECIES OF SCYPHOCRINUS 



It is an interesting illustration of the progress of discovery, and of the 

 liability to change of opinion resulting therefrom, that this genus, so profusely 

 illustrated by Waagen and Jahn, and supposed by them as well as by Schuchert 

 to be unknown outside of Bohemia, 1 now proves to be more widely distributed, 

 and represented by a far greater variety of species, in America than in Europe. 



The genus Scyphocrinites was proposed by Zenker ' in 1833, based upon 

 specimens from Bohemia which he described under the name Scyphocrinites 

 elegans, which should therefore be the type. Schlotheim had previously, in 

 1820, applied the name Pentacrinites excavatns to certain specimens said by 

 him to be the " Prague Encrinite," and to figure 2, plate 4, of Schroeter's 

 Vollstandige Einleitung, 1778, but without other description. Passing over 

 various allusions to these fossils in the intermediate literature, we have as the 

 chief source of technical information the elaborate work of Waagen and Jahn 

 in 1899, based partly upon the unpublished researches of Barrande.' Some 22 

 large quarto plates, with voluminous text, are devoted to the illustration and 

 description of the Bohemian forms of this genus, including a complete resume 

 of antecedent literature. 



For the purposes of the present paper Scyphocrinus may be briefly defined 

 as a Melocrinoid, with four basals; with branching, uniserial arms; and with 

 some of the tertibrachs, and perhaps higher brachials, incorporated in the 

 dorsal cup by means of a network or pavement of plates connecting those of 

 adjacent rays. This pavement is the most conspicuous feature of the calyx, 

 producing depressed, numerously plated, interbrachial areas above the level 

 of the axillary primibrachs, peculiarly modified by secondary growth, with 



1 Since their work appeared, fragmentary remains of Scyphocrinus and Lobolithus have been 

 reported from Cornwall, England, and also from Poland, Prussia, the French Pyrenees, Spain, and 

 India. 



a Beitrage zur Naturgeschichte der Urwelt, p. 26. 



s Systeme Silurien du centre de la Boheme, vol. 7 ; Scyphocrinus, pp. 35-97. 



