25 
is due the credit of having shown that they are a very special 
development of the tetradactylous pedicellariæ found in the genus 
Åræosoma, not primitive globiferous pedicellariæ as was assumed 
in the "Ingolf” Echinoidea. In my paper "On some Echinothurids 
from Japan and the Indian Ocean” (Ann. Mag. Nat. Hist., Ser. 7, 
Vol. XIV, 1904, p. 85) I wrote: "The form of pedicellariæ in Hapalo- 
soma described by me in the "Ingolf” Echinoidea (p. 55) as a primitive 
globiferous pedicellaria, not seeing its relation to the tetradactylous 
pedicellariæ, cannot, of course, any longer be regarded as a primi- 
tive form, now that the three-valved "tetradactylous” pedicellariæ 
of A. tesselatum and AÅ. owstoni have been made known. As rightly 
pointed out by de Meijere, it must be regarded as a case of 
extreme development, in which the valves have become rudimentary 
and the glands excessively developed”. 
Professor Agassiz's remarks on this form of pedicellariæ and 
his suggestion that it belongs to his "cystacanths” thus prove to 
be no more fortunate than his remarks on the "cystacanths” upon 
the whole. 
