249 



tapering to 015 inch at 035 inch from base of cup, from whence 

 downward no taper or expansion is visible. Joints of cohmin about 

 0.25 inch thick, slightly gibbous in centre; each joint consisting of 

 five pieces as in some species of lleterocrinus. 



This species agrees with Angelin's genus Eiispirocriaus in the ar- 

 rangement of the cup-plates, anal area, ventral tube and arms. The 

 brachial plates differ from those of the typical species in number, which 

 is only a specific difference. The author of the genus considers, as also 

 does Mr. C Wachsmuth, that the coiling of the arms, such as is shown, 

 on plate 4, fig. la of Angelin's beautiful Iconographia, as characteristic 

 and notable from a generic point of view; but as la of the same plate, 

 does not indicate this peculiarity, I look upon the failure of my speci- 

 mens to show anything beyond a tendency (such as is to be seen \y\ 

 Carabocrinui) to cni'l inwaid as not affecting the generic relations of this 

 species. 



This species is the first described from American rocks. Belong- 

 ing to a genus resembling Foteriocriaus, excepting in its lack of pin- 

 nulfe and differing from Dendrocrinus in its anal area, it is an interest- 

 ing addition to our list. 



Trentox Formation. — One of the two specimens collected was 

 obtained on Division Street, Rochesterville, and the other at Hall, 

 P.Q., in the C.P.R. cutting adjacent to the Aylmer Road crossing. 

 — Collector W. R. Billings. 



Genus ARCH^EOCRINUS. — Wachsmuth & Springer. 

 Arch^ocrinus Desideratus. — n.sp. 



Cup subglobose ; the breadth once and a-half the height. 



Basals, once and a-balf to nearly twice as long as wide ; five in 

 number ; hexagonal ; bent to an angle of 90° at about | of their 

 length from the column, the united basal plates forming for the first 

 portion of their length a cone surrounding the column, and their dis- 

 tal sides supporting the primary i-adials. 



Primary radials 3x5; the lowest series pentagonal ; the second 

 hexagonal; the third pentagonal, each supporting two rows of secondary 

 radials four plates to each row. Each row of secondary radials sup- 

 poi'ts two rows of tertiary radials having each two or three plates all of 

 which are included within the cup. The quaternary series are free. 



