NOTES ON ECHINODERM MORPHOLOGY. 158 
du test, qui, en ce point, n’est pas adhérente 4 la plaque mad- 
réporique.” He then goes on to say that the pores of the 
madreporite open into this space, which “semble étre tout 
@abord une sorte de cloaque dans lequel viennent s’ouvrir le 
canal du sable et le canal issu de la pointe supérieure de 
Porgane que l’on considére comme un ceeur.”’! 
Definite as these statements are, they appear to me to rest 
upon insufficient evidence, as did those of Hoffmann respecting 
the Starfishes. If the pores of the madreporite in an Urchin 
really do lead into a cavity which lies beneath it, and receives 
the ends both of the stone-canal and of the duct issuing from 
the ovoid gland, Perrier or Koehler could surely have obtained 
sections or other preparations? in proof of their assertions. 
They may have done so; but, as the fact is one of considerable 
importance, they would have done well to illustrate it by 
figures. Ludwig figures several sections through the madre- 
porite of a Starfish, and they completely bear out his statements 
which I have quoted above. Had Messrs. Perrier and Koehler 
done the same, the solution of the problem of the Echinoderm 
vascular system would have been very materially advanced. 
Ludwig’s remarks*® upon the possible fallacies of the injection 
method are very much to the point, and if the internal connec- 
tions of the pore-canals in the madreporite can be demonstrated 
in a Starfish a similar demonstration is surely possible in the 
case of an Urchin. But we have not had it as yet; and in the 
absence of this much-to-be-desired proof of the statements of 
MM. Perrier and Koehler I prefer to believe that the relations 
of the ovoid gland to the madreporite are the same in the 
Urchin as they are in the Starfish, according to Ludwig, 
i.e., that the ovoid gland does not communicate with the 
exterior. 
I have therefore practical reasons, besides the purely theo- 
1 * Arch. de Zool. Exp. et Gén.,’ t. iv, p. 613. 
? The dissection which is represented in fig. 1, of Perrier’s memoir, only 
shows: this infundibuliform space from the outside. A larger figure of its 
internal arrangements would be interesting. 
3 Loe. cit., p. 103. 
1] 
