18 



very slightly-raised riug-, aud immediately outside of that, by another 

 one so much elevated as to form a little cup, with a somewhat ex- 

 panded rim. Diameter of the largest plate in the collection, about twenty 

 millimeters. 



Spines very long, slender, one of the specimens having been, when per- 

 fect, about efeven centimeters in length, terete; diameter at the basal ring, 

 which expands abruptly from the shaft, much greater than any portion of 

 the latter ; shaft continues of nearly uniform diameter for more than half 

 its length from the ring, and then gradually tapers to a point. Greatest 

 diameter of the shalt of the long spine referred to, scarcely five mil- 

 imeters; diameter of the basal ring, seven millimeters. Surface of the 

 spine for a short distance above the basal ring apparently smooth, but 

 from that portion to the distal end it is ornamented with numerous 

 small points or incipient spinules. These are often removed by weath- 

 ering; but in well-preserved specimens they are quite distinct, and are 

 seen to be arranged in imperfectly spiral lines around the spine. 



Position and locality. — Carboniferous strata, Camp Apache, Arizona. 



PdLYZOA. 



Genus Glauconome Goldfuss. 



Glauconome NEREiDis {sp. uov.) — Polyzoary branching, the main 

 stem sending oft' branches at irregular intervals, these in like manner 

 sending oft" secondary branches less frequently ; the stem and all branches 

 bearing branchlets of the usual character in regular series at each side, 

 all of which are straight or a little curved; branches leaving the stem, 

 and branchlets the stem and branches, at nearly or quite uniform 

 angles of between sixty and seventy degrees ; branchlets opposite or 

 irregularly alternating, the intervals between them being a little greater 

 than the diauieter of the branchlets; non-poriferous side of the stem, 

 branches, and branchlets convex and marked by fine, longitudinal striie; 

 poriferous side of stem and branches bearing a row of pores along each 

 of their lateral borders, the number of pores being about twice as great 

 as that of the branchlets, but they are not placed in ])erfectly regular 

 order with them. The space between these two lateral rows of pores is 

 convex, and marked by scattered, dimori>hous pores, which are not more 

 than half as large as those of the lateral rows. Branchlets bearing a 

 row of pores at each lateral border of the poriferous side, which are a 

 trifle smaller than the lateral pores of the stems, and which, having 

 prominent borders to their apertures, give the branchlets a somewhat 

 knotted appearance. 



There is considerable difference in the size of the broken stems and 

 branches among the specimens ; but none of them, not even the longest 

 fragment, perceptibly diminishes in size toward the distal end. The 

 largest stem is about half a millimeter in diameter, and the smallest 

 not more than half that size. 



The branchlets are from one to three millimeters in length. 

 The whole extent of the branching of a polyzoary of this species is 

 unknown. The branches are merely excessively developed branchlets, 

 each occupying the place of one of them. As soon as a branchlet 

 reached beyond the ends of those upon either side of it, it began to 

 throw oft' branchlets from each of its own sides and became a branch. 

 1 '1 a few cases, these first branchlets of the new branch have joined with 

 the adjacent branchlets of the stem, forming a few irregular fenestrules. 

 ■This species dift'ers from G. trilineata Meek in being much branched, 



