302 
19 and in Greenland from about 8 to 18 mm . (The Maximum lenght 
of the Greenland-forms is stated by examination of comparatively 
few specimens.) 
I therefore consider that the name Littorina groenlandica, 
Menke, should be dropped. 
It is noteworthy that L. nedis attains on an average a larger 
size on the East-coast of Iceland, where the climate is most severe, 
than on the West-coast. I have collected specimens from both the 
East- and the Westcoast at different levels between tide marks, and 
from localities having about the same degree of salinity, 84°/oo to 
35 %o. The mean temperature for the Sea Surface is 
for the year 
for August 
for February 
on the West-coast 
on the East-coast 
5—6° C. 
ca. 3 ° C. 
ca. 10 ° - 
o 
p 
• 
o 
1 
ca. 1 ° - 
ca. 0° - 
The size of the largest specimens, one being taken out of 
every fifty, is as follovvs: 
on the West-coast (600 spe- 
cimens examined, from Isafjordr, 
Arnarfjordr, Breidifjordr, Faxa- 
fjordr). 
17,8; 17,5; 17; 17; 17; 17; 
16,6; 16,4; 16,3; 16; 15,8; 
15,8 111 ra - 
Average size of the 12 largest 
specimens: 16,7 mm - 
on the East-coast (800 spe- 
cimens examined, from Hamars- 
fjordr, Berufjordr, Bakkefjordr). 
19; 
19; 
18,8; 
18,5; 
18,3; 
18,3; 
18,2; 
18; 
17,7; 
17,5; 
17,5; 
17,3; 
17,2; 
16,8; 
16,8; 
16,7 m 
in. 
Average size of the 16 largest 
specimens: 17,8 mm - 
It is almost impossible to decide whether any given example 
of Littorina is fullgrown or not. By taking only the largest spe- 
cimen out of every fifty, I think there can be no doubt that my 
measurements have only comprised fullgrown specimens. 
The size recorded is the maximum length of the shell from 
the apex to the base of apertura. 
