C. Wachsmuth—Structure of Paleozoic Crinoids. 115 
Art. XVIL—WNotes on the internal and external structure of 
Paleozoic Crinoids ; by CHARLES WACHSMUTH. 
THE structure of fossil Crinoids has occupied the attention 
of many able writers, and numerous ingenious and plausible 
theories have been advanced to demonstrate the physiological 
functions of the various parts of their complicated organization. 
The results of investigations heretofore made have been by no 
means harmonious, and newly discovered evidence renders 
many of these theories wholly unsatisfactory. I have been 
favored with unusual facilities for obtaining accurate knowledge 
upon many of the questions involved in these researches, and 
therefore hope that I may contribute useful information on the 
subject. The collections of eighteen years at Burlington, Iowa, 
ave brought to light material, unrivaled elsewhere, for this 
study. I have obtained upwards of four hundred species of 
have led me to conclusions which I present in the following 
pages. 
1. The mouth and the tubular skeleton below the vault. 
The apparent absence of a mouth has proved to be one of 
the most perplexing points in the investigation of the structure 
visceral 
radiation and within the interradial area, where, from analogy, 
we must expect to find the anus. If, as Mr. Billings, 
White+ and the older writers on Crinoids supposed, this aper- 
ture served both as mouth and vent, so that these Crinoids 
* This Journ., 1869, vol. xlviii, No 142, p 
+ Journ. Nat. Hi 
. ee 
st. Boston, 1862, vol. vii, No. 4, p. 481. 
