with. Detailed plates have a length that is equal to about thirty times the great- est breadth, and are twice what corner form in outline, the widest end being that one which is exposed in the exterior of the sack. When the exceedingly delicate integument lining the interior of the sack, and to the outside of which the plates are attached is removed, the dinner ends of the plates are expanded; this side of the plates is provided with a slightly defined, longitudinal furrow. Specimens of this species are normally coated with iron, which effectively destroys their minute characters. Fortunately, the authors found some fragments that were entirely free of that trouble and solid and from these the details of its alveolar pattern were obtained. Named during the energetic collecting by Mr. H. E. Dickhaut. Formation and locality: The speci- mens were found in the shales of the lower part of the Hudson River group, at Crompton, N.Y., elevation about one hundred and fifty feet above low-water mark in the river's center. 10-22 Lepradelites elongatus. Believed This species differs from the type of the genus mainly in its different form. The form of L. dickhauti is sub-spherical, while that of the species under consideration is sub- cylindrical, with the ends more or less somewhat termi- nated. The length is generally about equal to about three and a half times the diam- eter in transverse measure- ment. The specimens are crated with iron, and for that reason I was unable to ascertain whether the plates differ from those of the type species. Their arrange- ment is very much the same. This species seems to have attained a larger size than L. dickhauti. The largest specimen found, though defective at both ends, in its flattened condition is nearly two inches in length, by three fourths of an inch in width. Formation, locality and collectors: Same as the last.