322 
P. HERBERT CARPENTER. 
Some disputed points in Echinoderm Morphology. By 
P. Herbert Carpenter, M.A., Assistant Master at 
Eton College. 
The last number of the ^ Zeitschrift fiir wissenschaftliche 
Zoologie ’ (Band xxxiv. Heft 2) contains two valuable papers^ 
on Echinoderms, by my friend Dr. H. Ludwig, of Bremen. 
Many new observations of the highest interest are here 
recorded, and it is not too much to say that their accuracy 
may be relied on with the utmost confidence. But, at the 
same time, I believe that some of the conclusions which 
Ludwig has drawn from them are essentially unsound ; and 
in the following pages I propose to state my reasons for this 
belief. 
In the first place, however, I desire to state that some of 
the observations recorded by Ludwig in these papers have 
convinced me that certain views which I have advocated 
in the pages of this journal are no longer tenable. Four 
years ago Ludwig described some tubular appendages of the 
water-vascular ring of the Crinoids as opening below into 
the body cavity into which they depend ; and he therefore 
considered them together with the water-pores of the disc as 
collectively representing the madreporic apparatus and sand 
canals of the other Echinoderms. 
Like Greeff, however, I did not feel quite satisfied respect- 
ing the alleged opening of these tubes into the body cavity, 
as I knew from my own observations of them (made like 
those of Ludwig by the section-method) that the liability to 
error was considerable. But now that Ludwig has found 
them to be open in the uncut Pentacrinoid larva I see no 
reason to doubt that the same is the case in the adult. 
Consequently, the resemblance^ that I, like Professor 
Huxley, believed to exist between these (apparently caecal) 
tubes and the closed oasa ambulacralia cavi of the Ophiurids 
will not bear investigation. 
But, while abandoning this position, I must still confess to 
a lingering doubt as to whether the disconnected water-pore 
and water-tube of the Antedon larva can be regarded as 
perfectly homologous with the madreporic system of the 
other Echinoderms. I fully admit the similarity of their 
* “Ueber den primaren Steincanal der Crinoideeu uebst vergleicliend 
anatomischen Beraerkungen iiber die Echinodermen iiberbaupt/’ pp. 310 — 
332, Taf. xii u. xiii. “ Neue Beitrage zur Aiiatomie der Ophiuren,” pp. 
333—30 5, 'I’af. xiv — xvi. 
^ This Journal, vol. xix, New Ser., p. 10. 
