322 PROCEEDINGS OF THE ACADEMY OP [1879" 



Geological position, etc. Known only in the Upper Silurian of 

 Sweden, where it is represented by the two following species: 



1878. Botryocrinus ramosissimus Angelin. Iconogr. Crin. Suec , p. 24, pi. 20, 

 fig. 8 and PI. 23, fig. 14. Upper Silur. Gotland, Sweden. 



1878. Botryocr. corallum. Angelin. Iconogr. Crin. Suec, p. 24, pi. 15, fig. 9, and 

 pi. 23, figs. 15, 16, and pi. 24, fig. 4. Upper Silur. Gotland, Sweden. 



B. Subgenus SICYOCRINUS Angelin. 

 1878. Iconogr. Crin. Suec, p. 23. 



Sicyocrinus cucurbitaceus Angelin, the only known species of 

 this type, is so closely related to Botryocrinus that we think it 

 should be placed thereunder as a subgenus. The calyx, in form 

 and arrangement of plates, is alike in both, and even the arms and 

 ventral sac are constructed upon the same plan, but which is dif- 

 ferently executed. 



In Sicyocrinus there are five single arms, in place of five pairs, 

 which give off branches from one side only, and not alternately 

 from both sides as in the typical form. The branches, which are 

 represented up to the fourth order, diverge from the arm at a less 

 angle, and those of the third and fourth orders are comparatively 

 longer. The brachials, as well as the arm joints throughout the 

 branches, are from two to three and even four times longer than 

 wide, and have a deep ambulacral furrow. The ventral sac, as in 

 Botryocrinus, first ascends, then turns abruptly toward the pos- 

 terior side, and bends until its extremity points downwards. It 

 is now very remarkable that the portion of the tube which is bent 

 over is not only firmty attached exteriorly to the lower part by a 

 growth of plates, but it appears that its inner passage followed 

 the curvature of the tube, for on each lateral surface there are two 

 rows of fissures which follow exactly the line of deflection. Col- 

 umn obscurely pentagonal. 



1878. Sicyocrinus cucurbitaceus Angelin. Iconogr. Crin. Suec, p. 24, pi. 4, fig. 

 9, and pi. 16, fig 5. Upper Silur. Gotland, Sweden. 



13 BARYCRINUS Wacbsmuth. 

 (Diagram PI. 1, Fig. 3.) 



1868. Proc. Acad. Nat. Sci. Phil,, p. 338. 



This genus was founded upon a group of Crinoids which had 

 formerly been referred by Hall and Meek & Worthen to Gyatho- 

 crinics, differing, however, from it in several strongly marked fea- 



