106 Forty-fourth Report on tee State Museum, 



Ohio (see op. cit. plate 13, fig. 7), from which all the marginal and 

 terminal spines were lost and the pustulous surface worn away. The 

 original of Mr. Meek's D. Ohioensis, from the Corniferous limestone at 

 Marblehead, Ohio, was a pygidium, the surface of which was also worn 

 smooth, but retained the marginal spines. An abundance of these 

 pygidia from Ohio and various localities in New York (especially 

 from the Lime Rock quarries near Le Roy) rendered their specific 

 identity beyond question. In some material from Ohio which had 

 been loaned by Dr. Newberry was a single fragment, comprising 

 nearly one-half of a cephalon, from the Corniferous limestone at 

 Columbus. This retained one very large and greatly elevated eye, 

 and showed agreement with the original of Asaphus aspectans in all 

 the features known. There was no other known trilobite in these 

 rocks to which this cephalon could be referred with any confidence 

 of accuracy, and hence it was presumed that this was the cephalon 

 belonging to the pygidia passing under the names of D. Helena 

 and D. Ohioensis. Its identity with Asaphus aspectans was beyond 

 contravention. 1^ 



Quite recently the State Museum has obtained possession of an 

 entire individual of this species, which has an interesting bearing on 

 the validity of this identification. This fine specimen was secured 

 in the fall of this year by Mr. Albert L. Arey, of Rochester, N. Y., at 

 the quarries at Lime Rock. It consists of two portions, the intaglio 

 retaining the crust, and none of the important parts are missing. All 

 details of structure are well retained, the thinness of the crust show- 

 ing even the finer tuberculations of the surface. This animal, judging 

 from the dimensions of the pygidium, appears to be of about average 

 size, having a length to the extremity of the horns of the posterior 

 crescent of 5| inches. To this must be added a fraction due 

 to the slight compression of the posterior portion of the 

 thorax, and the original length of the animal was undoubtedly 

 fully 5 1 inches. The character of the cephalon confirms in 

 every respect the identification made in Volume VII. The marginal 

 border is very broad, narrowing into short cheek-spines, and the 

 entire surface of border, cheeks and glabella is coarsely tubercled. 

 The margin itself is regular and uninterrupted, as in Dalmanites 

 Calypso, Hall, of the same fauna, and in D. micrurus. Green, of 

 the Lower Helderberg; not crenulated as in the Lower Helderberg. 

 D. pleuroptyx, Green, the Schoharie grit species, D. anchiops, Green, 

 nor spined for its entire extent, as in D. dentatus, Barrett, of the Lower 

 Helderberg, nor baculiferous, as in D. regalis, Hall, of the Schoharie 

 grit and D pygmceus, Hall, of the Corniferous, nor dentate on its 



