446 
EDITH M. MUSGRAVE. 
exhibit, under normal conditions, certain controlled move- 
ments of the colony apart from the mere expansion and con- 
traction of the zooids. 
The earliest account of such movement was given by 
Lancaster^ (1601) who, on attempting to pluck up a growing 
Virgularia, observed it to ‘^shrink down to the ground 
uidess held very hard.” 
A later account of the movements of the colony was given 
by Bohadsch (1761, p. 424) who makes the following state- 
ment with regard to the conduct of a living specimen of 
Pennatula phosphorea in sea-water; 
“ The trunk was contracted circularly at the bottom of the 
naked part of the stem, and by this contraction formed a zone 
of the most intense purple, which moved upwards and down- 
wards successively. When it moved upwards through the 
length of the pinnated trunk it there became paler, and at 
length terminated at the top ; the motion being scarce finished, 
a like zone appeared at the end of the naked trunk, which 
finished its motion in the same manner as tlie former.” 
The peristaltic dilatation and contraction thus originally, 
described by Bohadsch has been confirmed by Kolliker, 
who suggests that the boi-ing in the sand is effected by this 
means, but the statement also made by Bohadsch in the same 
publication that a specimen of Pennatula was seen “swim- 
ming freely with all its delicate transparent polypi expanded 
sailing through the still and dark abyss by the 
delicate and synchronous pulsations of the minute fringed 
arms of the whole polypi ” still requires confirmation, although 
Ellis and Solander (1786), in the diagnosis of the genus 
Pennatula, state: 
“This genus of animals differs remarkably from all other 
zoophytes by their swimming freely in the sea, and many of 
them have a muscular motion as they swim along-. I know 
of none of them that fix themselves by their base.” 
In his account of the Penuatulidae in the ‘ Cambridge 
Natural History’ (Ccel en terates, p. 360), Hickson writes: 
' See Darwin, ‘Naturalist's Voyage round the World,’ p. 99, 1845. 
