224 
stages of development are passed there. The larve grow 
until the full number of adult body segments has been pro- 
duced and then enter upon the pelagic post-larval stage. 
This is the earliest known stage of development of the com- 
mon lugworm. The young worms do not settle down to their 
littoral habitat and characteristic mode of life until they 
have attained a length of about 5 to 7 mm. Young speci- 
mens 17mm. long have been found in the sand in June. 
Although it is difficult to estimate their age, it may be 
suggested that these specimens 17 mm. long and others up 
to 44 mm. long taken near the end of June were probably 
produced from ova laid in the preceding February or 
March. If that be the case, then worms five or six inches 
long are probably about a year old. Some of the large 
deeply-pigmented specimens obtainable at low spring tides 
are certainly much older, but on this point no information 
is available. It may be taken that the smaller specimens 
of Arenzcola used as bait are at least a year old. Con- 
sidering the abundance of Arenzcola on many beaches, it 
is astonishing that we know so little of its life history, and 
that so few post-larval’stages have been taken in the tow nets. 
The present state of our knowledge does not permit 
one to make any suggestions with regard to the possibile 
cultivation of lugworms in any given area in which they 
are wanting. The writer has made several attempts to 
fertilise artificially the ova of the common lugworm 
removed from a ripe female, by adding spermatozoa 
obtained from a mature male, but without success, 
although both ova and spermatozoa appeared, when 
examined microscopically, to be quite ripe and favourable 
to the experiment. Others have also experienced these 
failures when dealing with this and other species of 
Arenicola.* Evidently, therefore, it is more difficult to 
* I eventually? succeeded in fertilising artificially the eggs of 
A. claparedii. For an account of the early stages of development of 
this species, see under development. 
