PROCEEDINGS OF THE SOCIETY. 501 



pleasure of seeing and examining the microtome, and it seemed to 

 him to be a most perfect and useful little instrument. 



The President considered one of its advantages to be that it 

 maintained the temperature at the same point for a much longer 

 period than most others. 



Dr. P. Herbert Carpenter gave an account of his views respecting 

 the nervous system of the Crinoidea, which he illustrated by diagrams 

 drawn upon the board, and by numerous preparations exhibited under 

 Microscopes. He directed attention more particularly to the branches 

 from the axial cords of the skeleton, which extended upwards into the 

 ventral perisome at the sides of the ambulacra both of the arms and 

 of the disk. The material was chiefly derived from the collection of 

 the ' Challenger ' expedition, and the results when complete will be 

 embodied in the volume in course of preparation. 



Dr. Carpenter, C.B., said he was very glad that his son had brought 

 this subject forward, because it formed an extremely good illustration 

 of the value of microscopical investigation where important questions 

 had to be determined. In this instance a great deal hung upon the 

 point whether these cords were nerves or not ; for if they were, then it 

 was clear that the whole of their present system of classification of 

 Echinodermata must undergo revision, because all morphologists had 

 been trying to show the analogy of this group to the star-fishes, of 

 which they were considered to be only a family. He had, however, 

 always held, from a careful study of them during the last thirty 

 years, that the general structure of the crinoids was formed upon a 

 plan very different from that of the star-fishes. Of the various argu- 

 ments which his son had brought forward to prove the truth of that 

 idea, the anatomical argument was the most important, as being a 

 confirmation of what he had himself previously advanced ; for it 

 must be remembered that at the time to which he had referred, many 

 things could not be demonstrated because they had not then known 

 how to cut thin sections. Very early in his investigations he had 

 found that a cord which had been discovered by Miiller, and consi- 

 dered by him to be a nerve, was a genital rachis, which would develope 

 afterwards according to the sex of the specimen. But by the adoption 

 of thin section-cutting a flattened band was discovered beneath the 

 ambulacral groove, which all the German observers, and Professor 

 Huxley also, at once concluded to be the nerve, because a nerve ought 

 to be there. In the star-fishes it certainly was so ; but it was certainly 

 not the only nerve in crinoids. He was early led to regard as a nerve 

 a cord running continuously through the calcareous segments of the 

 arm, and originating in a central organ in the base of the calyx. 

 This organ, which is an expansion of the summit of the original 

 crinoid stem, is divided into five chambers, from the outer walls of 

 which proceed five radial branches ; and these branches inosculate with 

 each other laterally so as to form a circular commissure from which 

 branches are given off to the arms, thus establishing a nervous con- 

 nection amongst them all, of which no one could doubt the existence 

 who has ever seen these feather-stars in the act of swimming, or simul- 



