PREFATORY NOTE 



Durinu the progress of Vol. V, part ii, some new material came into the hands 

 of the author, as well as better specimens of some forms already described and 

 illustrated. In order to render available the knowledge thus acquired, a few 

 supplementary plates were lithographed, with the expectation of being permitted 

 to publish them, with the necessary text, within a short time after the appear- 

 ance of the volume at the end of 1879. Unforeseen obstacles in the way of 

 any publication prevented these being made available, and this interruption 

 finally prevented the completion of the Supplement upon the plan originally 

 intended. The material thus prepared was laid aside, and the manuscript notes 

 and observations, made at that time, preparatory for the printing, were mislaid 

 or lost. 



In 1883, after the passage of the law to limit and complete the Paleontology 

 of New York, provision was made for incorporating these plates, with the 

 necessary descriptive matter, into the work, as a supplementary part of Volume 

 VII, where they now appear. The plates are numbered in consecutive order 

 from cxiv to cxxix inclusive, the last plate of Vol. V, part ii, being cxiii. A 

 single plate is devoted to the more complete representation of the Pteropoda, 

 embracing figures in farther illustration of some species already described, 

 together with others of new forms. 



During the progress of Vol. V, part ii, the study of the Pteropoda, especially 

 of the genera Tentaculites and Styliola, had suggested the importance of a 

 review of these genera and an inquiry into their relations with Cornulites. 

 It was not until the discussion of the genus Tentaculites had been nearly 

 completed, and the tabular arrangement of species in type, that the author 

 became fully aware of the necessity of this revision and of a farther inquiry 



