388 
crispata L., is, according to Mørch"), recorded by Olafsen from the 
tract between tide-marks at Faxefjordr. 
Systematical remarks. 
With regard to Dendronotus arborescens it must be noted 
that on a specimen which I examined the number of lateral teeth 
was very small, viz. 7, on each side. This is, as far as I know, 
the smallest number which hitherto has been observed in that 
species. R. Bergh?) records the range of variation of the 
number of denticles on each side from 14 to 21, and Posselt?) 
extends it to 9—25. 
As to the systematical relation of Littorina arctica, Møller, 
I have in a previous paper”) drawn the attention to the forms 
intermediate between this and Littorina obtusata L. : 
Respecting the systematical relation of Bucecinum groenlandi- 
cum, Chemnitz (B. cyaneum, Bruguiére) I must maintain that its 
range of variation is in contact with that of Buccinum undatum, 
L. The distinguishing marks between these two forms may be 
drawn up as follows: 
Buccinum groenlandicum Buccinum undatum 
1) Longitudinal folds on the shell | 1) Longitudinal folds on the shell 
wanting, or very short. ; well. developed. 
2) Number of denticles on late- | 2) Number of denticles on late- 
ral plates 3. ral plates 4. 
3) Number of denticles on all 3) Number of denticles on all 
three teeth at most 12. three teeth at least 13. 
1) 0. A.L. Mørch: ,,Faunula Molluscorum Islandiæ”. Vid. Medd. Na- 
turh. Foren. Kjøbenhavn. 1868. 
2) R. Bergh: Die Nudibranchiaten. Gesammelt wåhrend der 
Fahrten des ,,Villem Barents" ete.  Bijdragen tot de Dierkunde. 
Amsterdam 1 
3) H. Posselt: Grønlands Brachiopoder og Bløddyr". Meddelelser om 
Grønland. 23. Hefte. Kjøbenhavn 1899. 
+) A: C. Johansen: ,,0n the ERE observable in some Northern 
species of Littorina", Vid. Medd. Naturh. Foren. Kjøbenhavn 1901. 
