368 PROCEEDINGS OF THE ACADEMY OP [1879. 



23. (?) CYRTIDOCRINUS Angelin. 

 1878. Iconogr. Crin. Suec, p. 20. 



This genus is not only very imperfectly known a single calyx 

 only having been thus far discovered but it also deviates so 

 materially from all other Cyathocrinidae, that we doubt whether 

 it can be properly classed with that family. According to Angelin 

 it has four underbasals, which are small and unequal in size. 

 Basals five, pentagonal or hexagonal. A single anal plate is inter- 

 calated between two basals and two radials. Radial s five-sided, 

 oblique, clypeiform. 



1878. Cyrtidocrinus facietatus Angelin. Iconogr. Crin. Suec, p. 20, pi. 21, figs. 

 13, 14, 14 a. Upper Silur. Gotland, Sweden. 



24. (?) PACHYOCRINUS Billings. 

 1859. Geol. Surv. Canada, Dec. iv. p. 22. (Not Pachycrinus Eichwald.) 



In the single specimen to which Billings applied the above name, 

 there are five pentagonal plates concealed within the cavity for 

 the attachment of the column, and above and alternating wdth 

 them five very large, thick plates, which may be either basals or 

 radials. The lower portions of these plates are bent under the 

 body, so as to constitute a broad, rounded, or concave bottom to 

 the cup, wdiieh has a width of nine lines at a height of two. At 

 this level the cup is broken off in the specimen. 



Billings refers to this genus: 



1859. Pachyocrinus crassibrachialis Billings. Geol. Surv. Can., Dec. iv. p. 22, pi. 

 1, figs. 1 a, b. Chazy Limest. Montreal, Canada. 



25. (?) MYELODACTYLUS Hall. 



1851. Geol. Eep. New York, Pal., vol. ii. p. 191. 

 1878. Angelin, Iconogr. Crin. Suec. p. 11. 



(Herpelocrinus Salter, 1873, Cab. Mas. Camb., p. 118 is synony- 

 mous with Myelodactylus, according to Angelin. ) 



Hall proposed the above generic name to characterize some 

 most remarkable fragments, apparently arm pieces of Crinoids, in 

 which, according to his description, " the foramen or medullury 

 canal penetrates the column of joints." No other portion of the 

 animal was known to him. 



Angelin, for reasons unknown to us, referred to this genus 

 three species, and gave the following generic descriptions, " Gene- 

 ral form of the body narrow, elongate ; calyx cup-shaped. Basals 



