150 W. B. Dwight — Discovery of fossils in the 



Pygidium of moderate size, triangular ; axis strong elevated, 

 obconical ; with at least two well-impressed transverse furrows 

 near the anterior end, forming there two conspicuous annular 

 lobes, and apparently in some specimens, another faint furrow 

 still farther to the rear. No tubercles detected. The lateral 

 lobes consist of an inner depressed-convex portion, much lower 

 than the axis, traversed by two or three oblique furrows corres- 

 ponding with the spines, the posterior one, however, quite 

 faint, and a perfectly flat and moderately broad margin from 

 which three flat and acute spines extend backward. These 

 much resemble the pleural spines, but have a less graceful 

 appearance from the tendency of their edges to run into 

 straight lines. The two posterior spines, one on each side, are 

 about as far apart as the width of the axis of the pygidium at 

 its anterior end ; the border of the posterior margin which 

 unites them, is nearly or quite a straight line. 



Quite a number of specimens have been collected of the 

 glabella and pygidium of this trilobite, in which the features 

 as here described are quite constant. Only one has been found 

 (fig. 5) which exhibits the contour of the complete cephalic 

 shield, and two which show the thoracic segments. 



On account of the imperfection of the head and pygidium 

 of the more complete specimen, No. 180 (which I will con- 

 sider, in any event, the type of the species " Stissinge?isis"), 

 there might be doubt concerning its specific identity with the 

 others. Specimen No. 182 is a link, however, which seems to 

 remove all question from the evidence. The name assigned to 

 the species is that of Mount Stissing, near whose base it 

 occurs. 



The close affinity of this trilobite to the type Olenoides JVeva- 

 densis *M.eek, is very evident and interesting. The main points 

 of difference are : (1) The more slender and tapering thoracic 

 axis. (2) The shape of the axial thoracic segments, and the 

 arrangement of the furrow in these segments. (3) The broad, 

 flat pleural thoracic spinous processes. (4) The different struc- 

 ture of the pygidium. 



The glabella and fixed cheeks are also considerably unlike 

 those of " Ogygia serrata " Rominger, which Mr. C. D. 

 Walcott, after careful comparison of specimens, considers to 

 be identical with Olenoides Nevadensis.\ From the calcareous 

 shale, and rarely in the compact limestone. 



8. Discovery of Calciferous Fossils in the Millerton—Fishkill lime- 

 stone belt / also in a belt near Rhinebeck. 



The Hillsdale-Copake belt of the original Taconic limestone, 

 dividing just south of Copake, enters the northeast corner of 



* See Bulletin No. 30, U. S. Geological Survey, Plate xxv, fig. 7. 

 f This Journal, III, vol. xxxvi, 1888, p. 165. 



