NATURAL SCIENCES OF PniLADELPHIA. 91 



with the smallest elevations and depressions of the internal cast, 

 from which the foregoing description was drawn np. 



Locality and position. Upper part of the Corniferous group, 

 Sylvania, Lucas County, Ohio. Devonian. Mr. Gilbert's collec- 

 tion. 



DALMANITES OHIOENSIS, Meek. 



Pj'gidium large, depressed, semi-elliptic or semi-oval in general 

 outline, nearly straight or gentl}^ convex in outline on the ante- 

 rior margin, with the lateral angles a little rounded ; posterior 

 extremit}^ somewhat raised and truncated, with the lateral angles 

 of the truncated margin produced into two rather sliort, distinctly 

 converging spines. Mesial lohe narrow, or only equalling half 

 the breadth of each lateral lobe at the anterior ends, depressed 

 and graduallj^ tapering to the posterior end, which terminates 

 very near tlie truncated posterior margin ; rather distinctly sepa- 

 rated 1)y the furrow on each side from the lateral lobes ; segments 

 about eighteen, passing straight across, and separated by Avell- 

 defined furrows, that are narrower tlian the segments themselves, 

 which are not furrowed. Lateral lobes most convex along some- 

 what within the middle, where they are nearlj^ or quite as high as 

 the mesial lobe, toward which they slope slightly on the inner 

 side, while beyond the middle they sIojjc off gradually to the 

 lateral margins, which are very narrow, not thickened above, and 

 curve outward nearly horizontal!}^; segments al^out fifteen, widen- 

 ing slightly outward, and separated V>y deep, well-defined furrows 

 extending very nearly to the lateral margins ; the larger ones 

 showing faint traces of a slender longitudinal furrow along the 

 middle, while all, excepting a few of the smallest posterior ones, 

 are produced beyond the lateral margins in the form of slender, 

 sharp rounded spines, that curve a little backward and upward. 

 Surface nearly or quite smooth. Thorax and cephalic shield 

 unknown. 



Length of pj^gidium, 1.10 inch; breadth, 2.10 inches; height 

 or convexity, 0.25 inch; breadth of posterior truncation, 0.45 

 inch ; length of longest spines projecting from lateral margin, 

 0.38 inch. 



This Trilobite seems to be closely allied to D. myrmecophorus 

 (= Asaphus myrmecophorus), Green, to which I was at one time 

 inclined to refer it. A careful comparison, however, with the 

 18TL] 



