628 TRANSACTIONS LIVERPOOL BIOLOGICAL, SOCIETY. 
on the 3rd, 5th, 7th, and 10th segments, exactly as in 
the Port Krin Polydora larvae (those on the 3rd segment 
being, moreover, rather smaller than the rest, as in the 
Port rin larvae), it is likely that these also belong to a 
species of Polydora. 
MAGELONID. 
Magelona (PI. III., fig. 39). Nectosoma.—The 
nectosoma stages of Magelona have been fully described 
by Claparéde (1863: pp. 74-77; Pl. X., figs. 9-14; PI 
XI., figs. 1-2), and subsequently—under the name 
Prionospro tenwis—by Fewkes (1885: pp. 167-172; PI. 
I.); that Fewkes’ larvae belong to the genus 
Magelona and not to Prionospro has been pointed out by 
Giard (1886: “Sur le dévelopment de Magelona 
papulicorns”’; Bull. Sci. du Nord, XVIL{ipaeee 
McIntosh has also examined some stages in the 
development of this larva (1894: pp. 66-71; Pl. VIIL., 
figs. 1-3). The youngest stages known appear to have 
been described by Claparéde only. On Pl. X. (fig. 9) he 
figures a larva about 1,000 in length, the mouth is wide 
and occupies the whole of the extreme front end of the 
head; it is surrounded by long cilia, and the ventral lip 
is deeply cleft. A tuft of long cilia occurs a little in 
front of each of the pair of bunches of long provisional 
setae with which the first segment is armed. The first 
19 segments each carry a ventral band of cilia near their 
posterior margins, and are followed by three atrochal 
segments, and the anal segment with a very strong band 
of cilia. No tentacles have yet appeared, and setae are 
confined to the first segment. 
The earliest stage seen by Fewkes was 2000-3000 in 
length, and in it all the cilia appear to have atrophied. 
Very long, slender tentacles, covered with spine-like 
