142 
SIDNEY F. HARMER. 
Northumberland material. Reproduction by fission appears 
to take place so frequently in these specimens that all the 
observed individuals may well have been produced in this 
way. It would thus be unsafe to assume that primary indi- 
viduals metamorphosed from larvae have so restricted a 
muscular region as that of their fission-products. This may,, 
however, be the case ; and it would be desirable to bear in 
mind the short muscular region and the tendency for its 
proximal end to be slightly invaginated, should the oppor- 
tunity occur of examining recently metamorphosed specimens 
from this part of the British coast. 
Observations which I have attempted to make on this 
subject have led to no definite result. By the kindness of 
Prof. W. C. McIntosh, F.R.S., I have been able to examine 
specimens of Ac tin otr ocli a branchiata from St. An- 
drews ; and amongst them I have found one or two specimens 
which have recently completed their metamorphosis. There 
appear to be no sufficient reasons for referring these speci- 
mens to P. oval is. I have also examined three recently 
metamorphosed Phoronis kindly lent to me by Prof. J. 
Graham Kerr, F.R.S., who obtained them on the West 
Coast of Scotland, off the Island of Arran. The number of 
tentacles in these specimens seems to be not less than twenty- 
eight to thirty, and there is no obvious differentiation of 
muscular and non-muscular portions in the metasome. The 
evidence thus appears to indicate that the specimens in 
question do not belong to P. ovalis. 
De Selys-Longchamps (1903, p. 43) has convinced himself 
that Actinotrocha branch iata is the larva of P. mulleri, 
a species described by him from Heligoland, but not, so far 
as I am aware, at present recognised as a member of the 
British fauna. In the same memoir (p. 47) he has advanced 
reasons for believing that A. pallida, Schneider, is not the 
larva of either P. hippocrepia or P. gracilis; and he 
suggests that it may belong to P. ovalis, if that form is 
really a distinct species. His statement (p. 47) that the 
worm produced by the metamorphosed larva of A. pallida 
