CRUSTACEA. 37 



of the latter species was accompanied by a figure, no violence is dune to Mr 

 Conrad's determinations by according recognition to the latter name. 



Distribution. Upper Helderberg group. Corniferous limestone: near Clarks- 

 ville, Albany county ; Schoharie. Schoharie county ; Caledonia, Monroe count \ ; 

 Lime Rock, near LeRoy, Genesee county; Clarence, Erie county; Falls of the 

 Ohio, Columbus and Marblehead, Ohio. 



Dalmanites (Coiionura) myrmecophorus. 



PLATE XI A, FIG. 13; PLATE Mil, FIG. 12 ; PLATE XIV. FIGS. 1-6; \ni> PLATE XV, FIGS II. 



Asaphus myrmecophorus, GtKebn, Suppl. Monog. Trilob. North America, p. Hi. 1835. 



Asaphus.' acanihopleurus (acantholeurus, in error), Conbad. Fifth Ann. Rept. Pal. N. Y., \<. 48. 1841. 



DaJmniiiii mynnecophorus, Hall. Descr. New Species of Fossils, etc., p. HO. 1861. 



Dahnania myrmecophorus, Hall. Fifteenth Rept. N. V. State Cab. Nat. Hist., p. SS. 1862. 



Asaphus? acantholeurus, (Conrad) Hall. Fifteenth Rept. N. Y.StateCab. Nat. Hist., |>. 113. 1862, 



Dalmanites myrmecophorus) Hall. Illustrations of Devonian Fossils, pi. xiii, figs. 15, 16. 1876. 



Dalmanites acantholeurus, Hall. Illustrations of Devonian Fossils, pi. xix. fig. 14. 1876. 



The Cephalon and Thorax of this species have been observed only in a condi- 

 tion so fragmentary as to be unsatisfactory for description or positive 

 identification. 



Pygidium large, sub-ovate-triangular, broadly emarginate behind. Surface 

 depressed-convex, scarcely flabellate, conspicuously trilobate. Posterior 

 limbus with an upward curve, which begins at the posterior third of the 

 shield and terminates in a vertical spiniferous border. 



Axis relatively narrow, width about one-fifth the width of the shield upon 

 the anterior margin ; evenly tapering to a termination which becomes obso- 

 lete within the posterior border. Composed of sixteen to nineteen broad 

 transverse annulations, separated by narrow, deep furrows. 



Pleura broad, most convex at about one-third their width from the axial 

 margins, thence rapidly sloping and becoming somewhat flattened near the 

 edge; composed of fifteen to eighteen broad annulations, which widen 

 toward their distal extremities, and in some instances show traces of a taint 



