Holopea planidorsata, n. sp. Description: Shell small, of three or four whorls wound in a moderate spire; apical angle about 90°. Base hemispherical, with a very tiny umbilicus or none. Whorls flat and horizontal on top, with the shoulder rather sharply rounded. The ambitus is just below the shoulder, and from here to the axis of the base the whorl is strongly and evenly convex. Each whorl rises about three-fourths its height above the succeeding, and the sutures are deep. The younger whorls are more evenly rounded than the last one. Aperture entire and vertical. Inner lip thin and recurving so as to enclose a very narrow hollow axis, or to form a columella. Surface marked by very fine and even lines of growth that have a strong retral arch on the upper side of the whorl, but are nearly straight and vertical from the ambitus to the umbilicus. Dimensions: Height, 15 mm.; width, 15 mm.; height of aperture, 8 mm.; width of same, 9 mm. The flattened shoulder and deep suture of this species are distinctive. Occurrence: Rockhouse shale, at Rockhouse, on Horse Creek, Hardin County. Diaphorostoma quadrangulare, n. sp. Plate IV, figs. 20, 21 Description: Shell low-spired, consisting of between three and four gradually but rapidly expanding volutions. In cross-section the whorls are rounded subquadrangular. The upper side is very gently convex and horizontal, the outer side is almost. vertical and is marked by an undefined median slightly concave zone. The base is as broad as the top and almost horizontal, but a little more strongly convex than the top side of the whorl. The four angles of the whorl are rather broadly rounded. The aperture entire, subquadrangular, and slanting somewhat obliquely backward below. Inner lip smooth. Base perforated by a narrow umbilicus. Surface marked by fine lines of growth and uneven coarser varices of growth which cross the whorl with a gently sinuous course, being gently convex forward at the center of the upper and outer sides, concave forward over the rounded shoulder, and broadly concave forward across the base of the whorl. Dimensions: Height, 37 mm.; width, 33 mm.; height of aperture, 27 mm.; width of same, 20 mm. Occurrence: Rockhouse shale, at Rockhouse, on Horse Creek, Hardin County. CLASS CRUSTACEA SUBCLASS TRILOBITA FAMILY PHACOPIDÆ Dalmanites purduei, n. sp. Plate V, figs. 1, 2 Description: Species of very large size. Cephalon semielliptical, with moderately long sharp genal spines and with a slight prolongation of the anterior margin in front of the glabella. Glabella large, depressed convex, most elevated between. the palpebral lobes, and descending with even curvature to the front. Front lobe transversely elliptical, a trifle over three-fifths as long as wide, and marked by three shallow subcircular pits. The deeper of these is in the median line and just back of the center of the lobe, while the others are so shallow as to be scarcely visible, and one is near the center of each lateral half of the lobe. The first glabellar furrow deep and extending nearly three quarters of the distance to the axis. The second, third, and fourth glabellar lobes are well fused at their extremities, the second and third lateral furrows being reduced to mere oblong pits upon the glabella. Cheeks with rather strongly arched slopes and with a gentle concave zone bordering the margin. Occipital furrows deep and wide. Eyes large and elevated. Lateral facial sutures lying in a distinct groove. Surface in all the specimens exfoliated, but the cast of the free cheeks roughened by shallow dimples. Pygidium subtriangular in outline, and ending in a blunt spine. Number of segments in the axial lobe varying from seventeen in a small specimen to twenty-two in the largest one. Dimensions: A mature cephalon measures 81 mm. from occipital ring to front margin; 130 mm. across the head at the eye lobes, 60 mm. between the eyes. The largest pygidium has a length of about 100 mm. and a width of 105 mm. A smaller entire individual has a length over all of about 120 mm. Discussion: This giant trilobite may be readily distinguished from the associated specimens of D. pleuroptyr by the facts that the second, third, and fourth glabellar lobes are confluent at their extremities, and that the facial sutures lie in distinct grooves. The fusion of the glabellar lobes indicates that this species belongs to the group of D. anchiops, D. stemmatus, and D. dolbeli, whose characters have been discussed by Clarke. The new species is remarkable not only for its great size, but also for the degree of fusion of the glabellar lobes at this early horizon. Occurrence: Ross limestone, at Olive Hill, Pyburns Bluff, and other localities in Hardin County. Dalmanites retusus, n. sp. Description: Species known only from the pygidium, which is semi-elliptical in outline, broader than long, and evenly rounded. behind without any spinous extension. Axis low, only slightly arched, rapidly tapering, marked by fourteen or fifteen annulations, the last of which are very indistinct as the axis becomes obsolete posteriorly. Pleura gently arched, marked by ten or eleven broad ribs separated by narrower grooves, all of which become obsolete before reaching the edge, leaving a smooth margin about 4 mm. wide. Dimensions: Length, 27 mm.; width, 41 mm.; convexity, 5 mm. Discussion: The absence of a spinous extension of this rounded pygidium is sufficient to distinguish it from all other species of Dalmanites except D. aspinosus of the Decker Ferry of New Jersey. Compared with this much earlier form, the pygidium of the new species is proportionately wider and more. broadly rounded behind, its axis tapers more rapidly, and it possesses a smooth marginal border. Occurrence: Occurs sparingly in the Birdsong shale at Perryville, Big Lick Creek, Birdsong Creek, the old Swayne's mill locality, etc. Plate I Fig. 1.-Zaphrentis parsonsensis, n. sp. Lateral view of a natural cast of the interior of the corallum. Fig. 2.-Apical view of the same. Fig. 3.-Favosites foerstei, n. sp. Lateral view, showing the subhemispheric base of the corallum. Fig. 4. Basal view of the same, showing the subcentral point of attachment and the wrinkled epitheca which covers the base. Fig. 5.-Pleurodictyum trifoliatum, n. sp. A mature colony attached to one valve of Rhipidomella oblata. The apex of the initial corallite is visible between the lateral corallites. Fig. 6.-Pleurodictyum trifoliatum, n. sp. An abnormal one-celled individual which was not cemented to any solid object, x 2. The lateral nodes, one on either side, are the aborted lateral corallites. Fig. 7.-Another colony of the same species, with the three corallites mutually contiguous. |