NOTES ON ECHINODERM MORPHOLOGY. 147 
account of its relation to the excretory gland. It appears to 
me, however, that Teuscher’s identification of the canal with 
columnar epithelium, found by him at the apical pole, as the 
water-tube, is more correct than Koehler’s view of what is 
evidently the same structure.” 
The words in italics were omitted by Koehler in his quota- 
tion, and he thus entirely altered the meaning of my sentence. 
I never referred directly to ‘‘the stone canal” of Spatangus, 
as would appear from Koehler’s quotation; and had I done so, 
I should never have given this name to a tube which commu- 
nicates, not with the water-vascular ring (auctorum), but 
with the excretory gland at one end, and with the oral blood- 
vascular ring at the other. Not wishing to be dogmatic, I 
avoided giving a definite name, as Koehler has done, to either 
of the canals between the oral rings and the madreporite. 
Koehler, however, first attributes to me an expression which I 
purposely refrained from using (7.e. in propria persona), 
and then interprets it according to his own ideas, which I am 
far from sharing. 
In writing of ‘the organ which is commonly called the 
stone-canal of Spatangus,” I was merely referring to the 
homologue of the glandular canal of Echinus. ‘Teuscher! 
calls it the ‘‘ Steincanal,’”’ and noted the presence of a second 
vessel by its side where it les along the gullet. Hoffmann? 
gave this name to the two vessels together, not having been 
able to differentiate them; while Koehler’ speaks of the “canal 
du sable” as double along the whole length of the gullet, but 
as single for the rest of its course until it joins the organ of 
excretion, just like the glandular canal of Echinus, with 
which both he and I believe it to be homologous. 
I was perfectly right, therefore, in referring to it as the stone- 
canal of authors. But as all agree in describing its connection 
with the ovoid gland, and I do not believe that this organ 
1 Loe. cit., p. 534. 
2 “Zur Anatomie der Echinen und Spatangen,” ‘ Niederl. Archiv f. Zool.,’ 
Bd. i, 1871, pp. 85, 86. 
> * Recherches,’ p. 92. 
