164 Part [11.— Twenty-first Annual Report 
With the exception of 3a the stage of each of these young crabs was 
known, since they were reared in the Laboratory from the Megalops 
stage. They are not, however, successive casts of one individual. 
The crab 3A was found on the beach, and from its size it is probably 
a specimen of the third stage. It cast in confinement, and the resulting 
form appears in the Table as 4a. 
Food of Megalops. 
In the feces of a Megalops there was a large quantity of diatoms. 
Rate or Growrn oF Carcinus nuenas. 
In the growth of the crab a considerable amount of variation occurs. 
This is due to the fact that increase in size only occurs after a moult, 
and the amount of the increase varies not only with the individual, but 
also in the same specimen in different moults. It is, however, possible 
with a fair amount of certainty to separate the crabs into year groups, as 
will be shown later, if attention be given in the case of small crabs to 
the month in which they are captured. 
In 1884 Brook published a series of observations on the rate of growth 
of Carcinus. He confined a number of specimens until they passed 
through a series of moults. He at that time wrote—“ It would appear 
impossible to judge either the age of any particular specimen, or the 
number of ecdyses which it had passed through, from a casual observa- 
tion of it on the sea coast, and even in confinement a number of ecdyses 
must be passed through before any reliable information is obtained.” 
He was of the opinion that two of his specimens which he reared from 
the Megalops stage, A and B, would have reached the breadth of 35 and 
56 mm. respectively when two years old. 
For several years Mr. H. J. Waddington, Bournemouth, has devoted 
attention to the rearing of this form. He has succeeded in obtaining 
a very complete and valuable series of casts of various specimens. The 
results of his work he has courteously communicated to me, and with 
his permission they are incorporated in the present paper. 
They refer to 11 individuals which were kept in confinement for 
periods varying from 7 to 34 months. ‘lhe particulars, consisting of 
the size* of each moult-stage and its date, are given in Table I. The 
first date and size refer in each case to the size and date of capture. 
For three Waddington series, viz. Nos. 8, 9, and 10, Table I., I am 
indebted to Meek’s paper on the “ Rate of Growth of the Crab.”T 
Alongside the measurement of each cast the ratio of increase is given, 
and the interval that elapsed between each two moults is appended. 
I have also arranged the data regarding five of Brook’s specimens in 
a like manner in Table IT. 
* The size consists in the Greatest Breadth of the Carapace. 
+ Northumberland Sea Fisheries Committee. Report on the Scientific Investigations for the 
year 1902. Newcastle-upon-Tyne, 1903, p. 58. 
[Ta BLE 
