58 A Contribution to thI' Lower Ukvoxian Faunas of Maryland 



border ; a narrow angular ridge extending from the extremity of the axis 

 into the acute spiniform caudal termination. The numl^er of articulations 

 in the axis is twenty or twenty-one, which are strongly defined, and some 

 of the anterior ones slightly bent forward, and sometimes a little more 

 prominent or almost nodose in the middle. Each of the lateral lobes is 

 marked by fourteen or fifteen (and, in one example, sixteen) ribs; the 

 anterior ones very regularly arching, while about four or five of the pos- 

 terior ones are turned backwards, approaching the parallel of the axis. 

 Each rib is marked by a narrow groove along its summit, continued to 

 where the ribs coalesce in the narrow marginal rim. The direction of 

 this suture, near the origin of the ribs, is a little below the middle, but, 

 in its course, approaches more nearly the upper margin. Surface granu- 

 lose, with a row of stronger granules or small pustules on each side of the 

 furrow marking the ribs, and still stronger ones on the middle of the an- 

 nulations of the axis." Hall, 1859. 



The gkl)ella is more truncate than in D. pleuroptyx. The chief and 

 most obvious distinction as figured and described by Hall is in the sharp- 

 ness of definition of the axial annul ations of the pygidium, but even this is 

 variable. This axis is also more prominent than in D. pleuroptij.T, espe- 

 cially the posterior extremity. 



Occurrence. — Helderberg Formation, Xew Scotland ( ?) Member. 

 Cumberland. Oriskany Formation, Eidgely ^NIember. Cumberland. 



Collection. — U. S. National Museum. 



Subgenus CHASMOPS McCoy 

 Dalmanites (Chasmops) anchiops (Green) 



Plate XCIIl, Fig. 5 



Calymene anchiops Green, 1S32, Mon. of Trilobites of North America, p. 35. 

 Asaphus laticostatus Green, 1832, ibid., p. 45. 



Phacops anchiops Burmeister, 1846, Die Organisation der Trilobiten, p. 90. 

 Dalmania anchiops Hall, ISfal, Description of New Species of Fossils, etc., 



p. 55. 

 Dalmania anchiops Hall, 1862, 15th Ann. Rept. N. Y. State Cab. Nat. Hist., 



p. 83. 

 Dalmanites anchiops Hall, 1876, lUus. Devonian Fossils, pi. ix, figs. 1, 3-6, 10, 



12, 13; pi. X, figs. 6-14. 

 Dalmanites (Chasmops) anchiops Hall and Clarke, 1888, Nat. Hist. N. Y., 



Pal., vol. vii, p. 59, pi. ix, figs. 1-6, 10, 12, 13; pi. x, figs. 1-14. 



