1912.] R. B. SEyMOUR-SEWELL: Surface-Living Copepoda. — 321 
=. 
Observed size. Calculated size. | Growth-factor. 
oereaeee | 
mm. | mm. 
Stage 5 ty a 0°840 0°840 1°4 
sch Zt os “ec EVES Si | 1°176 1°4 
Hat aS are oé 1°620 | 1'6406 1°27 
ieee ive ae 2°14 2°090 1°27 
ae ek a6 ac 2°640 2'654 
o 
Observed size. | Calculated size. Growth-factor. 
_— Ih = 
mim. mm. 
Stage 5 ate ; 0'84 0°84 Ok 
any: 5 ns 37, EeZ6 Teh Or he27, 
8 we se I°502 1°60 I'5 
eee afc sis 1°868 1°89 
ee 56 ie 2°342 | 2°40 
Here again we find exactly the same growth factors and the 
same dimorphic condition in the males, and from this it would 
appear by no means improbable that the growth factors remain 
constant for a given species under altered conditions, variations 
in the food-supply, etc., merely causing changes in the number of 
moults carried out in any given period of time. 
(6) Acrocalanus inermis, sp. nov. 
A considerable number of examples (367) were measured and 
the results obtained were plotted out as before (text-figure III). 
In this species I was only able to obtain a series of four 
growth stages in each sex and the final sexual stage, stage I, was 
not represented; but so far as these moults go they confirm the 
results obtained in the previous species. 
In the female the observed and calculated sizes for the various 
moults agree even more closely than in Labidocerva euchaeta. 
