282 PROCEEDINGS OF THE ACADEMY OF [1881. 



1839. Carpocr. simplex Phill. (Actinocr, simplex.) Apud Murchison, Silur. Syst., 

 p. 673, I'l. 18, fig. 8 ; Austin, 1843, Phoenicocrinites simplex, Ann. and 

 Mag. Nat. Hist., xi, p. 2C5; D'Oriiigny, IS.")!), Abracrinus simplex, Troclr. 

 Paleont., i, p. 47; Roemer, 1855. Carpocrinus simplex, Letluca (iuogn , 

 (Ausg. 3), p. 237; Salter, 1870, Taxocr. simplex, Cat. Geol. Mus. Canibr., 

 p. 125; Angolin, 1878, Pionocr. simplex, Iconogr. Crin. Suec, p. 5, pi. 15, 

 15 a. Dudley, England and Gothland, Sweden. 

 Syii. (?) Actinocr. tesseracontadactylus, Hisinger, 1837, (not Goklf.), Lethaea 

 Suecia, p. 90, PI. 35, figs. 4, a-b; D'Orbigny, 1850. Ichthyocr. tesseracon- 

 tadactylus, Prodr. Paleont. i, p. 46; Salter, 1847, Cyathocr. tesseraconta- 

 dactylus, Murchison's Siluria, (ed. iv), PI. 14, fig. 4. (We follow Angelin in 

 placing this species a synonym under Carpocrinus simplex.) 



*1878. Carpocr. tenuis Angel. (Habrocr. tenuis,) Iconogr. Crin. Suec, p. 4, PI. 

 26, figs, 9, 9 a. Upper Silur. Gothland, Sweden. 



*1878. Carpocr. umbonatus Angel. (Habrocr. umbonatus.) Iconogr. Crin. Suec, 

 p. 4, PI. 26, figs 13, 13 a. Upper Silur. Gothland, Sweden. 



Subgenus DESMIDOCRINUS Angelin. 

 1878. Angelin. Iconogr. Ci-in. Suec, p. 5. 



General form oblong to subovoid. Calyx short, saucer- or cup- 

 shaped ; sj^mmetry bilateral. 



Basals three, small, scarcely projecting laterall}'. Radials 

 3x5; the first large, polygonal ; the second short, linear ; the 

 third transverse, pentagonal. Secondary radials 2x10, one side 

 of each ray bifurcating again giving off two arms, the other a 

 single one. 



In D. jyenfadactylus both halves branch again, thus making 

 three arms to one half, and two arms to the other half division, or 

 five arms to the ray, and twent^'-five to the individual. 



Arms long, heavy, cylindrical, composed of verj^ short joints, 

 which sometimes become wedge-form and almost interlocking. 

 Pinnules very long, largely articulated. 



Interradial and anal plates not differing from Carpocrinus. 



Column strong, round, composed of alternate large and smaller 

 joints ; central perforation pentagonal. 



The subgenus Desrtiidocrinus differs from the tj'pical form in 

 the greater number of arms, and that these are given off unequally 

 from the ray, also in having somewhat longer arms with shorter 

 joints. 



Geological Position^ etc. — Only found in the Upper Silurian of 

 Europe. Angelin refers to it the following species : 



1878. Desmidocrinus heterodactylus Angel. Iconogr. Crin Suec, p. 5. PI. 16, 16 a. 

 Upper Silur. Gothland, Sweden. 



