1., PALEONTOLOGY OF NEW YORK. 



To Summarize the Characters: 



These organisms, in their earliest recognizable conditions of existence, appear 



:is a simple point or spec upon the surface of some other organism, becoming a 

 slender enrolled tube where the volutions (so far as can be determined) may be 

 in the same plane and having the form of Spirorbis, under which designation 

 they have sometimes been described. In its farther development the body 

 becomes an elongate, straight or sinuous tube. In the earlier stages these 

 orgaisms, either singly or in groups, remain attached to the surface of some or- 

 ganic or inorganic body, and the continuation of this parasitic condition depends 

 upon the size of the body or extent of surface upon which they may continue to 

 mow. Beyond the limits or extent of the surface affording means of attachment, 

 they heroine free and continue their growth in a constantly expanding tubular form. 



In their earlier stages the substance of the fossil consists of an inner and an 

 outer wall, which are in contact; the exterior becoming annulated at an early 

 period, and the inter-annular spaces, or the upper inner margin of these annular 

 growths, produce sharp interior annulations, which often extend considerably 

 within the visceral cavity, so that when the exterior becomes worn away, or 

 the fossil is cut through on one side of the center, they often give the aspect of 

 a septate tube. 



In the first recognized stages of this organism, the tube is apparently smooth, 

 hut in the later conditions the annulations are conspicuous and again become 

 gradually obsolete with the growth of the animal. The longitudinal striae, 

 which are at first obscure, become developed with the growth of the tube, and 

 continue a conspicuous feature after the obsolescence of the annulations. The 

 intermural vesicular tissue becomes developed only with the expansion of the 

 tubular growth, and especially after the organism has assumed a free condition 

 of growth. 



In their earliest known condition these bodies are always parasitic, and they 

 are not known to begin their existence as a free organism. Whenever, in their 

 advanced state of growth, they occur in a free condition, it will be found that 

 the initial point is wanting, having been broken off and the marks of the frac- 

 ture still remaining, or the surface has become cicatrised. 



