MONOGBAPII OF THE EXISTING CRIXOIDS. 119 



J. S. Miller in 1821 described in considerable detail the skeletal structure nf 

 Antedon bifida, of which he gives good figures, but he npj)ears to have made the 

 same mistake as Peron in regard to the mouth. 



In 1823 Leuckart, and also Meckel, correctly described the two openings of 

 the alimentary canal, their observations being independently confirmed by J. E. 

 Gray in 1826, in which year Heusinger published a more detailed discussion of the 

 same point. 



In 1825 the Rev. Lansdown Guilding of St. Vincent called attention to the exist- 

 ence of peculiar articulations in the comatulids in which the joint faces are marked 

 with radiating lines, but he evidently supposed that all the brachial articulations 

 of the comatulids are of this type. 



In 1832 Goldfuss studied in detail the calcareous structure both of Antedon 

 mediterranea and of Comanitms bennetti (" Comatula multiradiata"), giving excellent 

 figures of each, in connection with his great work on the fossils of Germany. 



In the following year Heusinger published his completed report upon the 

 anatomy of Antedon mediterranea, a report which, considering its early date, pos- 

 sesses very exceptional merit; and Leuckart contributed another memoir on the 

 same subject. Heusinger's paper is accompanied by the first colored figures of 

 recent crinoids ever published. 



De Blainville's account of Antedon in 1836 shows more or less ignorance of the 

 work of previous investigators. It had been a prevalent idea that the crinoids 

 grasped their prey with their arms, something after the manner of an octopife; 

 Lamarck believed this, but supposed that the food was conveyed to the mouth 

 by the action of the long oral pinnules, while de Blainville supposed that the actual 

 capture was performed by the tentacles bordering the ambulacra! grooves. His 

 description of the skeleton is fairly good and, like his predecessors, he abandoned 

 the curious idea of Lamarck that the pinnules are really polyps comparable to those 

 of the umbellularians; but, in spite of the excellent monograph of Heusinger, 

 he described the stomach as a blind sac, and considered the anal tube to be more 

 or less the homologue of the siphon of the cephalopoda, or a sort of ovarian 

 pouch. He was unable to find the ovaries; but they had been correctly placed 

 by J. V. Thompson (1835) in Antedon Vifda and by Dujardin (1835) in Antedon 

 mediterranea while his memoir was in course of publication. Dujardin at the time 

 he described the position of the ovaries also proposed the theory that the tentacles 

 bordering the ambulacral grooves serve to pass the food along to the mouth, and 

 in addition, from an examination of the excreta, determined the fact that the food 

 of A. mediterranea consists of micro-organisms. 



Prof. Johannes Miiller, with his characteristic energy and thoroughness, now 

 took up the study of the crinoids, and between the years 1840 and 1840 published a 

 series of most excellent morphological and systematic treatises, dealing particularly 

 with the skeleton and the skeletal connectives, laying the basis for the systematic 

 study of the crinoids, especially of the comatulids. He was the first to describe 

 minutely a recent pentacrinito (Isocrinus asteria). 



Prof. Edward Forbes in 1841 described A ntedonlnfida in considerable detail, 

 but without much regard for the work of pievious investigators: although the 



