Paleoiilolooy of the Ciiii iinia/i (iroup. 153 



(ic'ims 2. — DiCTYONEMA, Hall, 1S52. 



Fronds circular, flabclliforin. funnel-shaped or conical, 

 sometimes arranged in j^roups composed of radiating 

 l)ranclies, which frequently divide, but run nearl}- i)arallel 

 with one another; all the ])ranches united by delicate 

 transverse bars or dissepiments; cellules forming distinctly 

 angular denticles, arranged on the sides of the branches in an 

 alternate manner; frond rooted (?) ; substance corneous. 

 (Palentol. of New York, vol. 2, 1S52, p. 174. Enioid., Nichol- 

 son, Mon. Brit. Graptolitidic, 1S72, p. 129.) 



Remarks.— 'X\\^ genus was originallj^ described by Prof. Hall 

 as a coral, the type species occurring in the Niagara Group. 

 Prof. Hall noticed its resemblance to the Graptolites, how- 

 ever, and in 1857 referred the genus to that family.''^ Only a 

 single species has been recorded from the vicinity of Cin- 

 cinnati. This has been generally referred to as D. irrcgulaj'e, 

 but Dr. Gurley says it is not that species as it occurs in New 

 York. He places it in the species as given below with the 

 accompanying comments. 



I. — D. ARBUSCULUM, Ulricli (sp.) 1879. 



" Frond small, originating in a single stipe at the base, branch- 

 ing and spreading above ; branches varjdng in size, biit nar- 

 row, not exceeding two-one-hundredths of an inch in width, 

 with strong, prong-like projections rising from the sides at 

 variable intervals ; bifurcations numerous ; surface with faint 

 longitudinal or diverging corrugations irregularly distributed; 

 free extremities of branches usualh' pointed. (Jour. Cin. 

 Soc. Nat. Hist., vol. 2, 1879, p. 28; as Inocaulis arbuscuia.) 



" To this description I add the following from an examina- 

 tion of specimens in the cabinet of the late Mr. U. P. James: 



" Specimens consisting of a portion of the network, show- 

 ing it to be formed principally by the curving toward each 

 other of adjacent branches, dissepiments, however, being 

 present. In consequence of the curvilinear direction of the 

 branches the meshes have a rounded-oblong, or rounded-dia- 

 mond shape. Branches varying in thickness, but about two- 



*In the Rept. Prog. Can. Surv., 1S57, p. 142, where Grapiopoia, Salter wa.s noted as 

 a synonym. HaU al.so records the discovery of hydrothecse ("ceUules' and modi- 

 fies the original description to include these. R. R. G.) 



