THE DEVELOPMENT OF THE SKELETON IN THE 
GENUS WALDHEIMIA 
BY 
HERMAN FRILE. 
I. a short article of mine intitled: «Bidrag til Vestlandets 
Mollusker», published in «Videnskabs-Selskabets Forhandlinger» 
in 1875, it was pointed out, that the skeleton of Valdheimia 
cranium Moll. and Valdheimia septigera Lov. underwent a pecu- 
liar change, of such nature, that the apophysary system exhibi- 
ted a much more complicated construction at an early stage of 
growth than at that of maturity. 
My object then was merely to call attention to this faet. 
More extensive material, which later on has come into my hands, 
has enabled me to inquire still further into this interesting 
matter. My investigations are still unfinished, but as the Nor- 
.wegian North-Atl. Expedition will for some time to come pre- 
vent my pursuing them, I am here going to give a short 
preliminary account, which will restate and complete the obser- 
vations made in 1875. | 
Having resumed the study of the Valdheimia, I have be- 
come satisfied that my deseription given of the young state of 
the apophysary system and its developement was in the main 
correct, viz: the apophysis of the Valdheimia is at an early 
stage fastened in a threefold manner: firstly the lamellæ are 
