ICHTHYOCRINIDAE 313 



aberrant form of that genus, although the mode of arm branching and the interbrachial struc- 

 tures are against it. The specimen is much flattened, and the anal area distorted by pressure, 

 but relatively to the other areas its proportions are decidedly those of the present genus. 



Types. Author's collection. Collected by Rev. W. H. Barris, and presented for use in 

 this work. 



Horizon and locality. Middle Devonian, top layer of the traverse beds of the Hamilton 

 group ; Partridge Point, near Alpena, Michigan. 



Dactylocrinus tardus (Hall) 

 Plate XLI, fig. 11 



Forbeiiocrinus lobatus var. tardus Hall, Prelim. Notice 17th Rep. New York St. Cab. Nat. Hist., 1863, 



p. 7 (17th Rep., 1864, p. 56). 

 Forbesiocrinus tardus Hall, Hall and Whitfield, Geol. Surv. Ohio, Pal. II, 1875, p. 170, pi. 12, fig. 2. 

 Taxocrinus lobatus var. tardus, Wachsmuth and Springer, Revision Palaeocrinoidea, pt. I, 1879, p. 49. 



A large species. Calyx elongate, spreading upward; with rounded rays 

 and large ramules resembling arm-branches. Surface smooth. Crown about 

 31 mm. high by 15 mm. wide. 



The species is represented by a single imperfect specimen, too much flat- 

 tened and injured to afford full details of structure. The concave base with 

 IBB and BB hidden by the column, and the long, narrow post. B rising to the 

 height of the radials, proclaim its affinities with the genus. It has the usual anal 

 structure, though the plates are not preserved ; and it apparently had no inter- 

 brachials. There are 4 or 5 IIBr, and longer intervals between the ramules than 

 in any other species, being 6 or 7 brachials. The outer branches of the ray divi- 

 sions are slightly the larger, the ramules large, and the arm branching is strongly 

 in the direction of dichotomy. Column large, with very thin ossicles tapering 

 from the calyx. 



This is the last known survivor of the genus, being from the lowest member of the Lower 

 Carboniferous, and in its intermediate type of heterotomy it departs most widely from the 

 typical species. 



Type. New York State Museum, Albany. 



Horizon and locality. Lower Carboniferous, Waverly Group; Richfield, Cuyahoga 

 County, Ohio. 



