306 W. WOODLAND. 
stay at the Plymouth Marine Biological Laboratory in April, 
1904, and was produced by carefully rearing larve (derived 
from artificially-fertilised ova) in large jars, each provided 
with a Browne plunger, and daily supplied with fresh sea 
water obtained from outside the limits of Plymouth Sound. 
There is no necessity for me to describe in detail the methods 
adopted in rearing the larve of E. esculentus since the 
whole process has already been admirably described by 
MacBride in his important paper relating to the development 
of this species (15, pp. 288—292), and to this account I refer 
the reader. I wish to add, however, one or two remarks 
supplementary to MacBride’s description. Prof. MacBride 
carried out his work at Plymouth five years previously to my 
own visit there, and I was, on this account, able to benefit by 
his experiences as communicated to me by Mr. Smith, assist- 
ant at the Laboratory, who kindly initiated me into the 
practical methods of larva rearing. In my own case I was 
fortunate enough to secure at the first haul three or four ripe 
males and females out of about a dozen specimens of EH. eseu- 
lentus, and seeing that this was in April—a month earlier 
than the time selected by MacBride, when, as he says “ one 
was lucky if.one obtained a single ripe pair out of a haul con- 
taining over a hundred specimens ”—I think the fact is note- 
worthy. Again, I may mention that during the early stages 
of development it was found necessary, by means of Bolton 
silk, to strain off from the daily supplies of fresh sea water 
the flagellate aloa Phaeocystis globosa, since this was 
liable to become entangled with the larve. Later on, how- 
ever, when the plutei were about half grown, the same alga, 
broken up so as to release the spores, served as food, and, 
indeed, the plutei principally subsisted on this diet. As re- 
gards MacBride’s tabular scheme of the suecession of events 
given on page 293, I found it in general correct, so far as my 
observations of the earlier stages went, but Mr. Smith writes 
me that “some of the plutei (the eggs were fertilized on 
April 20th, 1904) hung on till the beginning of September, 
never looking robust but still healthy ”—a period after ferti- 
