303 
Littorina obiusata , Linné, Littorina palliata, Say, 
Littorina arctica, Møller. 
The name Littorina palliata, Say, must be applied to forms of 
the obtusata group having a short and obtuse spire. Say says in 
his description (4 p. 240): „spire short, convex, obtuse, much shorter 
than the aperture.“ In spite of this definition some authors, e. g. 
Sparre-Schneider (25) and Sars (20), have applied it to 
northern forms with pointed spire, and regarded it as synonomous 
with Littorina arctica, Møller. If the last named form should prove 
to be a variety of Littorina obtusata, then this species has a range 
of variation which would also include L. palliata, Say, hence it 
would be of no great importance to decide, whether L. palliata has 
a little more pointed spire than the common L. obtusata or not. 
At any rate it is a faet that many ot the American forms of ob¬ 
tusata can not be distinguished from the European ones. (See also 
Verkruzen 22.) 
As distinetive features between L. obtusata , Linné, and L. arc¬ 
tica, Møller (= L. palliata of Sars, Teilman-Friis etc.), in addi¬ 
tion to the elongated and pointed spire of the last named, the fol- 
lowing are recorded: 
Littorina obtusata, Linné 
1) On the first lateral tooth there 
is one long denticle next to 
the great denticle, near the 
central tooth. (G. O. Sars 20.) 
2) On the first lateral tooth there 
are two small denticles next 
to the above named long den¬ 
ticle. (Teilman-Friis, 28.) 
Littorina arctica, Møller 
1) On the first lateral tooth there 
are two long denticles next to 
the great denticle, near the 
central tooth. (G. 0. Sars, 20.) 
2) On the first lateral tooth there 
is one small denticle next to 
the above named two long den¬ 
ticles. (Teilman-Friis, 28.) 
Teilman-Friis has given a very good figure of the first lateral 
tooth of the two forms of Littorina, and has found the small inner 
denticles which thus far had been overlooked. The above named 
