1909. | OF THE LIMPET PATELLA VULGATA. 245 
Tasue V. 
Growth during July 1906 at Kames, Kyles ot Bute. 
| Fl | | igeeete 
| Group. Original Size. Final Size. | No. of days. | Bane 
[o— 5mm. A | Oi (ibe. | 
| | | | | 
femora eer 1,6. 26) sea 
| | 10 13 | 25 | 36°00 
wom 
| 12 | 125 31 | 4:03 
| | 4 
The observations recorded in Table I. amount to 42 for the 
month of August. 
The mean values calculated are given in Table VI. 
TaBLeE VI. 
Rate of Growth and Size. 
Fe = Growth per cent. | 
Group. No. | in30days. | 
0— 5mm. 1 | 30:00 
5—N0) x 2 16°84. 
10—15 _,, 5 19°20 
15—20 ,, 12 15°56 
20—25 ,, 17 19°42 
“25—30 ,, uit 6°89 
30—35_,, 5 5°05 
35—40_,, 5 4°77 
40—45 ,, 6 2°71 
45—50_,, 5 | 1:06 
69 
The percentages in the first two groups cannot be taken into 
account since the numbers are so small. From 10 mm. on to 
25 mm. there is a gradual and uniform falling-off in the rate ot 
growth. In the 25-30 mm. group there is a sudden fall of the 
vate to little more than half what it was at 20-25 mm., then 
there is another gradual decrease up to the length of 50 mm. 
There is a second slightly marked fall at a length of about 40 mm, 
4. Seasonal Variation in Rate of Growth. 
That the limpet grows more quickly in the warmer months of 
the year is a fact which 1s clearly shown by the data in Table I. 
In the first year-group for example, during the months of June, 
July, and August, the monthly increment of growth is about 
3 mm. During September the increment is 2°2 mm., during 
