387 
Buccinum undatum groenlandicum, Chemn. 
Dendronotus arboreseens, Mill. 
Archidoris tuberculata, Cuv. 
Lamellidoris bilamellata, Mill. 
Acanthodoris pilosa, Mill. 
Æolidia papillosa, L. 
Coryphella lineata, Lovén. 
Anomia ephippium, L. 
Mytilus edulis, L. 
Mytilus modiolus, L. 
Modiolaria lævigata, Gray. 
Cyamium -minutum, Fabr. 
Tellina calcarea, Chemn. 
Mya truncata, L. 
Sazicava arctica, L. 
Names of the species which occurred in the greatest abundance 
have been printed in roman types. 
Of the named forms Archidoris tuberculata and Coryphella 
lineata are new to the Icelandic fauna. 
Where the tract between tide marks has a vertical height of 
2—31/5 metres, as at Reykjavik and at Stykkisholm, Acmæa te- 
studinalis, Littorina rudis, Littorina obtusata and Purpura lapillus 
are most frequent above the low-water mark, and Buccinum un- 
datum, Skenæa planorbis, Mytilus edulis and Cyåmium minutum 
near the low-water mark. The rest of the species seems to oceur 
in gréatest abundance below that level. 
Of the named species 3 belong to Polyplacophora, 24 to 
Gasteropoda and 8 to Lamellibranchiata. While the number of 
Lamellibranchiata on the tract between tide-marks is to that of 
Gasteropoda as 1/3 the proportion is about ”/3 if regarding species 
living at a depth from 0 to 200 metres. 
One species which I did not succeed in finding, viz. Zirphæa 
5% 
