r912.]| R. B. SEyMOUR-SEWELL: Surface-Living Copepoda. 323 
Observed size. Calculated size. | Growth-factor. 
mm. mm. 
Stage 5 es So 0°49 0°49 115.5 
eae ie ae 0°66 0664 1°355 
ae: oe 56 c'90 | 0'900 1°208 
oiiea 2 1°08 1'087 1'208 
Aree! a8 a Unknown i ORIN: 
Here the growth-factors are 1°355 for the first two moults, 
while the last observed moult had a factor of 1°208 and in con- 
sequence the final sexual stage or stage I, at present unknown, 
should have a length measurement of 1°313. 
In the case of the male also the last sexual stage was missing, 
but the observed and calculated sizes for the preceding four 
stages are as follows :— 
Observed size. Calculated size. Growth- factor. 
mm. mm 
Stage 5 Be HC O51 o'5i aT 
a 4. on a 0°63 0°66 I*3 Or 1°208 
Pees Se ae ost 0°80 jo! 
goad 2 0°86 0°86 
» I 50 eat Unknown | 1*O4 ay ae 
The stage growths here follow exactly the same rule as in 
Labidocera euchaeta. At stage 4 we get a division taking place ; 
some individuals becoming at once sexually mature and reaching 
stage 2, others having an extra moult to stage 3 before presumably 
doing so at stage 1. The characteristic growth-factor in this case is 
I°3 with the single exception of the moult between stages 4 and 3, 
where it again is the same as in the final female moults, vzz., 1°208. 
The text-figure does not show any very definite demarcation 
between stages 2 and 3, owing to the two curves of variation 
overlapping to a considerable extent ; these two stages, however, 
can be easily recognized by their structural characters (vide infra). 
(c) Pontella andersoni, sp. nov. 
A fairly large number of individuals of this species were 
obtained from the tow-netting taken off Chittagong. I have, how- 
