53 
taking 100 samples distributed over the whole area outside the plant belt; on the 
latter I have not yet been able to make quantitative investigations, partly because 
this region is too shallow for the ship, partly because the apparatus is not adapted 
for such work. The results of the enumeration of the separate species are shown 
in tables I-III. It is easy to see that the number of the samples is not sufficient 
for the rarer animals, i. e. the larger; but it is sufficient for the smallest and 
more common aninals. To examine into this matter more closely, the average 
number with its average error for each species and for each station is given in 
the last column of the tables I—IIL These calculations have been made by 
Professor Johannsen's assistant, Miss J. Hempel. We see that for many of the 
commoner species, such as Abra alba, Solen pellucidus, Mya truncata, Cardwwm 
Jfasciatum, Nucula nitida, Philine aperta, Nassa reticulata, Pectinaria, worms, 
Ophioglypha, the calculations give very great exactness.. Among these species we 
have all the principal food species of the plaice. Miss Hempel's examination has 
even shown that usable results can be obtained for many of these animals from 
50 stations. The shortcoming in the enumeration of the individuals as a measure 
for their mass is the often very different size of these; we are of opinion, therefore, 
that better results are attained by determinations of the dry matter for 
each single species of the whole number found at 100 or 50 stations. From the 
knowledge we now have of Thisted Bredning, it will naturally contribute further 
to the exactness of the determinations, if the Bredning is divided into 3—5 sub- 
divisions according to the differences present, and if we take for each subdivision 
a number of samples proportionate to its area, so that the samples may represent 
equally large areas. 
VIIL Mass and composition of the bottom-fauna at different places in 
Danish waters. 
It will be seen from the Chart No. II, that the greatest rough weight 
or alcohol weight, including here the animals halfdried and with their shells, 
was found in the North Sea, namely 5368 gm. per 10 m.?, then comes a locality 
west of Samsø with 4406 gm.; a few places in the Limfjord have 3838 gm., 2918 
gm. and 2825 gm., namely east of Venø, Thisted in the autumn, Louns Bredning 
and Skive Fjord. Roskilde Fjord at Roskilde has 2254 gm. The deep parts of 
the Sound north and south of Øresund have 1274 gm. and 894 gm., another 
locality west of Samsø has 1053 gm.; the Kulhus channel at the entrance to Ros- 
kilde Fjord has 1297 gm., Sprogø 709 gm. Of the remainder, the open Katte- 
gat had 378, 284 and 427 gm., the open Baltic 170 and 80 gm.; Isefjord and 
Holbæk Fjord gave 444 and 269 gm. Naturally these numbers are not all suffi- 
ciently representative of the waters investigated; the localities in the North Sea, at 
Samsø and in Roskilde Fjord especially are too few. Regarding the details see 
