274 PROCEEDINGS OF THE ACADEMY OF [1879. 



*1878. Gnorimocrinus oblongatus Angelin. (Taxocr. oblongatus.) Iconogr. 



Crinoid., p. 8, pi. 20, fig. 17. Upper Silur. Gotland, Swed. 

 *1878. Gnorimocrinus ovalis Angelin. (Taxocr. ovalis.) Iconog. Crinoid, p. 8, 



pi. 20, figs. 13, 14, Upper Silur. Gotland, Swed. 

 *1878. Gnorimocr. punctatus Angelin. (Taxocr. punctatus.) Icongr. Crinoid., 



p. 9, pi. 23, figs. 4, 5 (fig. 27(?) ). Upper Silur. Gotland, Swed. 

 *1878. Gnorimocr. rigens Angelin. (Taxocr. rigens.) Iconogr. Crinoid., p. 9, 



pi. 11. figs. 7, 8. Upper Silur. Gotland, Swed. 

 *1878. Gnorimocr. Salteri Angl. (Taxocr. Salteri.) Iconogr. Crinoid., p. 9, pi. 



23, figs 1, la. Upper Silur. Gotland, Swed. 

 *1878. Gnorimocr. tubuliferus Angl. (Taxocri. tubuliferus.) Inconogr. Crinoid., 



p. 9, pi. 20, figs. 11, 12. Upper Silur. Gotland, Swed. 



8. FORBESIOCRINUS De Koninck &, Lehon. 

 (Diagr. PI. 15, Fig. 1.) 



1853. Foi-besiocr., De Kou. & Leli. Reckerches 8. 1. Crin. Belg., p. 18. 



1858. Forbesioer., Hall. Geol Rep. Iowa, vol. i. pi. 2, p. 628. 



1866. Taxocrinus, Meek & Worth. Geol. Rep. Illinois, vol. ii. p. 269. 



1878. Forbesiocrinus, Angl. Iconogr. Crinoid., p. 9. 



A. Typical form. 



Comparatively larger than any other genus of the Ichthyocrinidse. 

 Bod} - , including arms, broad, short, almost equilaterally penta- 

 merous. Calyx very large, plates heavy and nodose, radial por- 

 tions prominent. Underbasals three, small, hidden by the column, 

 two of them of equal size, the third smaller. Basals five, four 

 about equal, the one at the posterior side larger, rarely truncated. 

 Primary radials three to four by five, generally four, but varying 

 in number in the individual ; large, almost equal in size and form. 

 Secondary radials two, three, four, or more to the series, about 

 half as large as the primary radials, and of the same general form. 

 Tertiary radials smaller than those of the preceding order and 

 comparatively shorter, the rays becoming free at the second, third, 

 or fourth plate. Arms long, dichotomizing, infolding at the tips 

 so that their full length is seldom observed. They are composed 

 of single, short plates, slightly rounded at the back, with a deep 

 ventral furrow. Arm joints in corresponding subdivisions of the 

 same size, those in each succeeding order smaller by about one- 

 half. The sutures of the radial and arm plates strongly sinuate, 

 and partly occupied by additional patelloid plates. Interradial 

 area extending to the top of the tertiary radials, and composed of 

 a large number of plates, from ten to twenty or more, which de- 



