A Contribution to the Lower Devonian Faunas of Maryland G] 



From the Oriskany comes a nearly complete pygidium which bears a 

 close resemblance to all and Clarke's description and figures. This 

 pygidium has, however, a much stronger duplication of the pleural annula- 

 tions and the axial annulations are arched slightly medially. Neverthe- 

 less, the specimen must he placed here for the present, though it may 

 ultimately be shown to l)elong to another species. 



Occurrence. — Oriskany Formation, Eidgely Member. Locality un- 

 known. 



Collection. — Maryland Geological Survey. 



Subgenus HAUSMANNIA 



Dalmanites (Hausmannia) pleuroptyx (Green) 



Plate XCIII, Figs. 6-10 



Asaphus pleuroptyx Green, 1832, Mon. of Trilobites of North America, p. 55. 

 Dalmania pleuroptyx Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, p. 356, pi. 



Ixxiv, figs. 5 ?, 9 ? (not figs. 1-4, 6-8. 10-12) ; pi. Ixxv, fig. 1 ?, 1861. 

 Dalmanites (Hausmannia) , pleuroptyx Hall and Clarke, 1888, ibidem, vol. 



vii, p. 28, pi. xia, figs. 1-3. 

 Dalmanites pleuroptyx Weller, 1903, Pal. N. J., vol. iii, p. 295, pi. xxxii, fig. 1. 



Description. — " Head semicircular, with the posterior side concave, and 

 the posterior angles prolonged to the fifth or sixth articulation of the 

 thorax : frontal limb slightly concave, thickened at the margin. Glabella 

 convex in front ; length from the annulation to the anterior of the frontal 

 lobe, equal to the width of the frontal lobe, which is transversely oval : 

 transverse furrows strongly marked, the anterior one more deeply than 

 the others, and passing imperceptibly into the depression which circum- 

 scribes the frontal lobe : anterior lobe expanding, and becoming prominent 

 towards the inner angle of the eye ; the central lobe a little wider than the 

 posterior one. Occipital furrow narrow, shallow in the middle; its con- 

 tinuation in the posterior furrow of the cheeks being very strongly defined, 

 and becoming wider towards the exterior margin. 



" Eyes large, prominent, having an elevation of ten ranges of lenses, 

 while laterally there are thirty-seven ranges : the entire number of lenses, 

 in a specimen of medium size, is 311. Between the lenses there is a small 

 round granule marking each of the angles of a hexagon, which circum- 

 scribes the lens. The entire rim of the eve is much elevated above the cen- 



