﻿schuchert] siluric and devonic cystidea -^7 



p. i). He regarded them as the type of a new and peculiar class of 

 Echinoderma, differing in their composition from all others 'by the 

 absence of all regularity.' These remarkable, irregularly rounded, 

 bladder-like bodies, attaining" a diameter of several (up to [8) centi- 

 meters, have been figured by Barrande on [3 |>latrs. not yet published, 

 of his work (provisionally designated as plates 67 to 70). 



" Similar bodies were found later in the Silurian of North America 

 by James Hall; at first ( [872) he described them as Cystids [this is 

 an error, as the citation given seems to have reference to a paper on 

 Cyclocystoides] . later (1879) he declared them to be modified, 

 bladder-like, swelled roots of true crinoids, an air-filled swimming 

 apparatus. This view is also held, as I have learned through corre- 

 spondence, by the Vienna geologists, Professor W'aagen and Dr. 

 lahn, who have carefully studied the Bohemian Lobolithes and who 

 will publish the plates of Barrande with descriptions. . . . 



" In a letter from Zittel I learn that he also is now of the same 

 opinion as Hall, Waagen, and Jahn. 



" The 13 lithographed plates of Barrande, which I have seen, have 

 figures of many Lobolithes of natural size: they are globular, or 

 irregularly rounded cvsts or bulbs, with thick walls consisting of 

 small polygonal plates. Most of the capsules have the size of a 

 child's head ; the largest attain a diameter of 0.2 meter and over. 

 The plates, with their peculiar structure, when magnified, show that 

 we are here dealing with Echinoderma. A first inspection of many 

 figures might lead one to regard them as irregular mailed-capsules of 

 simple Amphorids, similar to Aristocystis, Deutocystis, etc. Against 

 this determination, however, there are two decided facts : I. The 

 mailed-capsules show no openings [they have many large openings] 

 but are completely closed. On one end they rested directly on the sea 

 bottom (they are as the description states ' cemented by the flattened 

 crown') [this is never the case in either Camarocriiiits or Lobolithus] ; 

 on the opposite side there arises a slender column, which may attain 

 a length of several meters. II. The column is five-sided, prismatic, 

 segmented, and has wholly the structure of an ordinary crinoid 

 column ; the single segments show on the articulating surfaces a cen- 

 tral opening (stone canal) and a regular five-rayed stellate figure. 

 This characteristic structure is entirely restricted to the class Cri- 

 noidea, and occurs in no other Echinoderma ; it is absent in the true 

 Cystoidea and in the Amphoridea as well. This fact indicates that 

 in the Crinoidea alone the ' chambered organ ', or the five-chambered 

 tube, extends from the base of the cup through the hollow segmented 

 column. In the Cystoidea, on the other hand, the pentaradial struc- 

 ture is restricted to the theca. 



