EXPERIMENTAL OBSERVATIONS ON PENNATULIDS. 449 
is very similar to that of Alcyonium and Corallium 
rub rum. 
The brothers Marshall (1882) in the classic memoir on the 
Oban Pennatulida gave admirable accounts of the canal 
systems of Pennatula and Virgularia, in which the obser- 
vations of Kblliker are to a great extent confirmed and 
supplemented. 
Jungersen, 1904, describes for the first time the canal 
system of Protoptilum. 
Gravier, 1906, gives an account of a curious modification 
in the arrangement of the canals in the Virgularian genus 
Scytaliopsis. 
Notwithstanding the valuable contributions which Kolliker, 
Marshall, Jungersen, and Gravier have made with regard to 
our knowledge of the general anatomy and arrangement of 
the canal systems of Peunatulids, their actual function still 
remained a matter of uncertainty. Experimental evidence has 
therefore been sought Avith the hope of obtaining some 
elucidation of this unknown problem. 
All species of the genera Pennatula, Pteroeides, Vir- 
gularia and Anthoptilum which 1 have had the oppor- 
tunity of examining ag’ree in the following respects : 
In the presence of the four large central canals — one 
dorsal, one ventral and tAvo lateral canals. The dors.pl canal ^ 
extends from the extreme base to the distal end of the 
colony, and is separated from the ventral canal by the vertical 
septum (figs. 12, 13, 14), and the septum terminates inferiorly 
by fusion ventrally Avith the connective tissue of the body- 
Avall, usually, as iu Pteroeides some little distance above the 
basal termination of the stalk (fig. 14), so that the extreme 
loAver portion of the stalk is occupied only by the dorsal 
canal. 
lu Pennatula rubra the vertical septum extends almost 
but not quite to the extreme base of tlie stalk (fig. 13). 
* I liaA'e used the terms “dorsal” and “A’entral” in accordance 
Avith Jungersen’s designation, Avhich is the reverse of that formerly 
adopted By Kolliker and other antecedent Awiters. 
