REPORT ON THE CRINOIDEA. 17 
with what we know of their origin; and it likewise fails to account for their relations in 
the adult Crinoid. If this fibrillar tissue were limited to the skeleton, there might be 
some reason in Ludwig’s suggestion. But it gives no rational explanation whatever for 
the extension of branches from the axial cords of the skeleton through the perisome of 
the disk and arms, up to the bases of the tentacles at the sides of the food-groove 
(Figs. 4-7, a’. Fig. 8; Pl. LIX. figs. 2-4, 6,7; Pl. LX. fig. 2—ad; Pl. LX. fig. 6, a’), and 
even as asserted by Perrier, into the tactile hairs borne by these tentacles." 
Ludwig’s theory too entirely fails to account for the elaborate arrangement of 
commissures which one finds in Comatula and Pentacrinus (Pl. XXIV. figs. 7-9; 
Pl. LVIII. figs. 1-3), and in a less degree in Bathycrinus (Pl. VIIb. fig. 4, cco), 
Rhizocrinus (Pl. Villa. fig. 6, cco, to), and Enerinus. Why should the first 
radials and the axillaries be in such special need of nutrition that the former should 
possess both interradial and intraradial commissures, and the latter no less than 
four cords, to say nothing of the transverse commissure? Five radial cords starting 
directly from the envelope of the chambered organ would surely serve all the necessary 
purposes of nutrition. As it is, however, each ray and indeed each arm is supplied by 
fibres from two of the primary interradial trunks. This complex arrangement receives 
no explanation whatever on Ludwig’s theory, though it is easily understood if we suppose 
that the axial cords are the means by which co-ordinated impulses reach the muscles 
from a governing centre. 
Their anatomical structure also favours this view. In a paper which was published 
some years before the discovery of ambulacral nerves in the Crimoids, Baudelot quoted 
Miiller’s description of the so-called arm-nerve (i.e., the genital cord), and apparently 
adopted it as correct.” But he also stated that he could not help being struck with the 
resemblance “ qui existe entre la structure du cordon fibreux central des bras et la cordon 
nerveux des autres Echinodermes.” He described its relations pretty accurately, and 
then proceeded to say “ Ainsi done chez les Comatules il existe des parties qui evidemment 
n’appartiennent point au systeme nerveux, et qui dans leur disposition aussi bien que 
leur structure offrent une analogie presque complete avec les cordons nerveux des autres 
Kchinodermes.” 
I do not know what reason Baudelot may have had for his conviction that the axial 
cords are evidently not of a nervous nature, unless he had implicitly accepted Miiller’s 
account of the nervous system of a Crinoid. A very little trouble, however, would have 
convinced him that this was totally incorrect. In fact Dr. Carpenter had referred to 
Miiller’s error four years before the publication of Baudelot’s observations, and had also 
mentioned that he had reasons for regarding the branching fibres proceeding from the 
axial cords to the muscles as probably having the function of nerves. Had Baudelot 
1 Comptus rendus, t. xevii. p. 188. 
* Contribution 4 lhistoire du systéme nerveux des Hehinodermes, Archives d. Zool. expér., t. i. p. 211. 
