202 Part I1I.—Siateenth Annual Report 
records of these three stations is that for Station IV. This difference in 
the numbers of the records of these young forms is satisfactorily explained 
by the fact that the greater number of the Barnacle tribe, in our seas at 
least, are to be found attached to rocks, stones, and other objects inshore, 
and that there the young are usually to be found. 
Formula (2) shows the total number of records of young Balani for 
each of the twelve months for all of the six stations :— 
Names of the Months, da & e ee eb Bees 
See aes 62 ¢ oee 
Total number of Records for each Month, 0.0. 1-27 14 107.4250 <0 os 
It is evident from the numbers in this formula that the Balanz hatch 
out principally in April, and that after April there is a rapid diminution 
in the production of larval forms, after which a more or less complete 
cessation takes place, there being not a single record for all the six 
months from September to February. 
Formula (3) shows the total number of records of young Balan for 
each of the seven years for all the six stations :— 
Numbers of the Years, - - - 1889. 1890. 1891. 1892. 1893. 1894. 1895. 
Total number of Records for aon Year, - 4 9 20 7 11 5 2 
The number of records for 1891 is greatly in excess of that for any of 
the other seven years, but'the reason for this marked difference does 
not seem to be very clear. 
But the records of young Schizopoda and Balan form a comparatively 
small part of the whole number. The largest proportion of the three 
hundred and forty records of young and larval Crustacea are those of 
various species of Decapods, as has already been stated. But resuming 
consideration of the young Crustacea, we find by an examination of the 
general Table of Distribution that with one exception there are no records 
for January and February in all the seven years and for all the stations. 
After this a sudden increase is observed over all the stations, so much so 
that in regard to two of the stations the maximnm of records is reached 
in April. From this time the number decreases somewhat till August, 
when a marked extension occurs over all the stations, the number after- 
ward gradually diminishing till November. In December there is a 
somewhat sudden drop to one or two records, or, in the case of two of the 
stations, to none atall. This sudden increase and subsequent continuance 
of the moderately high numbers of the monthly records till November is 
an indication that in March and April an extensive and more or less simul- 
taneous hatching of Crustacean ova takes place, and that it continues 
more or less all through the summer and autumn and on till about the 
end of the year. Of course it is not suggested that it 1s the same species 
that produces these young forms all the year through, but that the ova 
of different species hatch out at different seasons and thus keep up the 
supply of larval and young forms. The subjoined formule, prepared from 
the numbers in the Table of Distribution, show more clearly by the 
arrangement of the numbers in this way some of the special features 
referred to in the distribution of the young and larval Crustacea. 
Formula (1) shows the total number of the records of young Crus- 
tacea for each of the six stations, which are divided into inner and outer 
stations :— 
Inner Stations. Outer Stations. 
Number of the Stations, - - | Aaatens! 0 trod AC VS OV ATs exe 
Total number of Records for each ‘Station, - 70 ~=660 55 56 49 50 
