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the dish surrounded by a film of mucus. Although the 
mouth was open it was found impossible to induce the 
larvee to feed and they died as soon as the yolk in the 
stomach was absorbed, 7.e., about a fortnight after 
hatching, without having advanced beyond a_ stage 
showing three or four chetigerous segments (fig. 77). 
Post-LARVAL STAGES. 
Post-larval stages of A. marina are found in the 
surface waters of the sea, and are almost invariably 
enclosed in a mucous or gelatinous tube, which overhangs 
the worm at each end: The external diameter of the tube 
is from two to three times that of the animal. The young 
worm is capable of wriggling movements, which are not 
seriously impeded by the enveloping tube. 
The term * post-larval stage” was given by Benham 
to a stage in the development im which the animal 
possesses the full adult number of segments, and is 
divisible into an anterior chetigerous region and a 
posterior achetous region, or tail, but in which the gills 
are not yet completely formed, or have not even made their 
appearance. By this definition all the pelagic specimens 
of A. marina which I have examined, with one possible 
exception, are post-larval stages. This one, a Lytham 
specimen, 3°9 mm. long, bears the full complement 
(thirteen pairs) of gills, and all of them except the first 
two have become branched, being formed of two or three 
finger-shaped filaments (fig. 56). In this specimen 
also the annulation is well marked, and the prostomium 
proportionately smaller than in any of the other specimens 
examined. This animal has reached the end of the post- 
larval stage, and would doubtless soon have settled down 
to its littoral habitat. It is the only recorded specimen 
