88 FIFTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



DALMANIA ADSPECTANS. 



Aaaphus adspectans : Conrad, Annual Eei)ort Pala3ontology of New-York, 1841, 



pa. 49, pl.l, f. 9. 



Description. " A small portion of the buckler and one eye only is 

 '' visible; but the eye is of an extraordinary height, the margins 

 " parallel, and the lenses arranged in parallel longitudinal lines, 

 " small and very numerous." 



The eye of this trilobite is remarkably elevated and subcylindrical, mea- 

 suring i^fg- of an inch in height, -^^^ in diameter at the base, and ^jP^ at 

 the summit. Lenses very small, depressed, and surrounded by an elevated 

 line enclosing a hexagonal area. There are twenty-two lenses in a vertical 

 line from base to top, and as many as thirty rows can be counted in one 

 specimen : in another specimen the eye is a little smaller, and has twenty 

 or twenty-one ranges of lenses in a vertical line. The portion of cheek re- 

 maining is strongly tuberculated. 



Geological formation and locality. In the limestone of the Upper Hel- 

 derberg group : Schoharie and the Helderberg mountains. 



DALMANIA MYRMEGOPHORUS ( Green, sp.). 



Asaphus myrmecophorus : Green, in Anier. Jour. Sci. and Arts; and Supplement to 



Monograph of Trilobites, p. 16. 



The specimen from which Professor Green described this species was a 

 fragment of the pygidium, preserving "thirteen costal arches and fourteen 

 joints of the middle lobe." So far as I am aware, no entire specimen has 

 ever been found ; and all the fragments yet positively identified with this 

 species consist of parts, or nearly entire specimens of the pygidium. In one 

 specimen about three inches in length, twenty-four annulations can be 

 counted in the axis, and probably there were one or two more ; and in the 

 same specimen, twenty ribs may be counted in the lateral lobes. At the 

 anterior extremity, the axis is a little more than one-third as wide as the 

 lateral lobe. In one specimen, the width of the axis at the anterior border of 

 the pygidium is one inch and a quarter in diameter, and the lateral lobe is 

 more than three inches wide : when entire, the specimen must have been 

 nearly eight inches wide. 



The contour of the pygidium is moderately convex, the axis rising but 

 little above the convexity of the lateral lobes : these are concave towards 

 the axis ; but within a distance of half the width of the axis from the 

 dorsal furrow they acquire their greatest convexity ( which is increased 

 by a row of nodes), and slope with a gradual curve to near the margin, 

 when they become a little concave from the slight bending upwards of the 

 margin. The rings of the axis are strong, convex, and marked each by three 

 spines. The ribs are simple, gradually expanding towards the margin, and 



[ September, 



