CoBBOLD, on Actinotrocha, 
51 
Such^ in brief, are all the facts 1 am enabled to give in re- 
gard to tlie organization of these interesting little animals. A 
more lengthened examination would probably have supplied 
me with further particulars ; but having been anxious to 
watch their further development (at the time assumed possi- 
ble)^ they were placed for this purpose in a small glass aqua- 
rium^ in which situation they so effectually concealed them- 
selves in a tuft of Enter omorpka, that I never afterwards suc- 
ceeded in finding them. While on the move^ they frequently 
displayed a most eccentric attitude^ and when motionless, 
they rested on the caudal extremity in an upright position 
(figs, 2 and 3). 
In answer to some inquiries respecting the polyzoal rela- 
tions of this larva. Professor Allman has kindly furnished me 
with the following particulars : — " It appears to me/' writes 
Dr. Allman, " that there are so many points which militate 
against its being a polyzoon, that I do not at all feel disposed 
to place it in that group. The lophophore and epistome seem 
in favour of its polyzoal relations, but then we have the same 
organs in PJioronis, and the epistome here seems to me, if I 
rightly understand your figures, not to be homologous with 
the epistome of the Polyzoa, as it here looks toiuards the con- 
cavity of the lophophore, while in the Polyzoa it looks 
toivards the convexity. Then there is no- distinction between 
a retractile and fixed portion (polypide and cell), and no 
system of muscles such as we find in the Polyzoa, while the 
position of the arms is so very difterent, as, I think, in con- 
junction with the other points, to decide against our associa- 
ting this creature with the Polyzoa." 
Until very recently, I was not aware that a form of animal 
very similar to that I have here imperfectly described and 
figured, had been noticed by J. Miiller, and others, under 
the name of Actiaotrocha branchiata. My attention having 
been drawn to this circumstance by Dr. Carpenter, I find, 
upon reference to Miiller' s paper contained in his ^ Archiv ' 
for 1846, p. 101, that there can be no doubt that the creature 
found by me in the Frith of Forth belongs, at any rate, to 
the same generic type as his Actinotrocha branchiata. In the 
same journal for the subsequent year, 1847, some additional 
observations on the same animal are given by Wagener, 
whilst two apparently distinct forms are briefly noticed by 
Gegenbaur, in Siebold and Kblliker's ' Zeitschrift fiir Wis- 
senschaft Zool.,^ vol. v, p. 347. From all of these, however, 
I am inclined to think that the form here noticed presents 
sufficient differences to justify its being regarded as repre- 
sentative of a distinct species, though obviously belonging to 
