MORPHOLOGICAL PART. 141 
organ is lodged within the centrodorsal, and is covered by the rosette,* it is 
in Pentacrinus, which has no centrodorsal, contained in a cavity formed by 
the radials above and the basals below. The five chambers of Pentacrinus 
are not closed at the bottom, but are continued down the stem as five vessels, 
systematically arranged around a central axis. These vessels were regarded 
Fig. 3, position of the axial cords in the young Antedon rosaceus (after W. B. Carpenter); Fig. 4, 
their position in the adult (after A. M. Marshall); Fig. 5, in Zverinus liliiformis (after Beyrich). 
ed = centrodorsal; 7 = infrabasals; 6 = basals; R= radials. The dark lines show the arrangement 
of the canals in the dorsal cup. 
by Dr. P. H. Carpenter as homologous with the five openings around a single 
one on the underside of the calyx, and along the stem of Cupressocrinus, Myr- 
tilocrinus, and Gasterocoma. Among recent Stalked Crinoids a chambered 
* Tn most of the Comatule, the embryonic basals are metamorphosed into the structure known as the 
“rosette,” which is enclosed within the radial pentagon, so as to be not visible externally. 
