STUDIES ON POLYCHAT LARVA. 597 
Studies on Polychet Larve. 
By 
F. H. Gravely, M.Sc., 
Junior Demonstrator of Zoology in the Victoria University 
of Manchester. 
With Plate 14 and 3 Text-figures. 
Dorine July, 1907, whilst studying in a general way the 
pelagic larvee of Port Erin, my attention was specially turned 
to the Polycheet larve on account of their abundance and the 
difficulty I experienced in identifying them. As a result of 
this I spent part of the following summer in a more careful 
examination of these larve. I am publishing a systematic 
account of the results of this investigation elsewhere (Gravely, 
1909). Inthe present paper I propose to describe a young 
specimen of a pelagic species of Odontosyllis, and the 
‘vestibule ” and associated modifications of the anterior end 
of larvee of the Spionidz and Polydoride ; and in conclusion 
I shall discuss certain other points of general interest arising 
from the above investigations. As, however, there appears 
to be no account in the English language of the terminology 
commonly adopted in the description of polycheet larve, it 
will probably serve a useful purpose if the first part of the 
paper is devoted to this subject. 
TERMINOLOGY. 
Prof. Hicker (1897, pp. 74-76) distinguishes the following 
larval stages : 
