312 SMITHSONIAN INSTITUTION 



Other structural details are generally similar to those of D. oligoptilus, 

 except that here the ray divisions are more deeply rounded, diverge at a wider 

 angle, and do not taper so decidedly upward. The ramules are stouter, and are 

 given off at shorter intervals, one from every second brachial ; about seven are 

 visible before the arms infold, and there were probably ten or more in all. Prox- 

 imal columnals very thin. 



The description is made from a very good specimen from Senzielles, considerably larger 

 than the type (PL XLI, figs. 4a, b). I have copied Fraipont's type figure, but it is incorrect 

 , in representing ramules from every successive brachial ; the alternate plates are rather short, 

 and run to a sharp angle between the bases of the ramules ; these were overlooked by the 

 artist, but the text, as well as the diagrams on page 1 12 of Fraipont's paper, shows one ramule 

 for every two plates. I also suspect that the interbrachials are too large in Fraipont's figure ; 

 they are relatively wider than they appear in the diagram. The species is nearest to D. oligop- 

 tilus, being from a closely equivalent horizon; but the rounded base with thin edge of the 

 concavity, and the great difference in the ramules, will serve to distinguish it. 



The horizon of this species is the Frasnien limestone, in the lower part of the Upper 

 Devonian. It is associated with Melocrinus hicroglyphicus and several other species of the 

 Eifel limestone occurring in the upper beds of the Middle Devonian, or Stringocephalen-Kalk. 

 Specimens are very rare. Those figured are from Senzielles, and I have another fragmentary 

 specimen from Chimay. 



Types. Fraipont's original was formerly in the collection of Professor G. Dewalque 

 of Liege. The other specimen figured is in the author's collection. 



Horizon and locality. Lower part of Upper Devonian, Frasnien ; Senzielles, near Couvin, 

 and Chimay, southern Belgium. 



Dactylocrinus alpena n. sp. 



Plate XLI, figs. 10a, b 



A medium-sized species. Crown elongate, height to width at about the 

 fourth axillary, 1.6 to 1 ; of calyx at I Ax, about 1 to 1.5. Ray divisions about 

 equal, with but little taper ; axillary plates wider than those next preceding. 

 Rays and their main divisions in close contact at least as high as the third bifur- 

 cation; all brachials from IBr up have a median elevation, sloping to the sides, 

 and are flanked by prominent lateral buttresses which interlock at the inter- 

 brachial sutures. IIBr 3, exceptionally 4. Ramules five or six in number, at 

 intervals of 4 or 5 brachials; large, resembling the main arm branches, and two- 

 thirds as wide. iBr few, usually 1 ; small, angular, with rays closely abutting 

 above them. Surface smooth except for the angularities on brachials. Anal 

 structure and base not exactly known. Holotype about 30 mm. high by 18 wide 

 at about the second ramule. 



This species is founded upon a single specimen consisting of a complete set of arms, 

 with base broken off; it was found on the beach of Lake Michigan at Alpena somewhat 

 weather-worn, and the rays appear more rounded dorsally than they probably were originally. 

 The arm-branching shows a distinct tendency toward dichotomy, in which it differs from all 

 the preceding species, as well as in the marginal sculpturing of the rays. In the latter feature 

 it much resembles Synaptocrinus mtntius, and there is a possibility that the species is an 



